CA2038023A1 - Linear viscoelastic aqueous liquid detergent compositions, especially for automatic dishwashers, of improved high temperature stability - Google Patents

Abstract

LINEAR VISCOELASTIC AQUEOUS LIQUID
DETERGENT COMPOSITION, ESPECIALLY FOR AUTOMATIC
DISHWASHERS, OF IMPROVED HIGH TEMPERATURE STABILITY

ABSTRACT OF THE DISCLOSURE
Automatic dishwasher detergent composition is formulated at a linear viscoelastic, pseudoplastic, gel-like aqueous product of exceptionally good physical stability, low bottle residue, low cup leakage, and improved cleaning performance, Linear viscoelasticity and pseudoplastic behavior is attributed by incorporation of cross-linked high molecular weight polycarboxylate acid type thickener. Potassium to sodium weight ratios of at least 1/1 minimize amount of undissolved solid particles to further contribute to stability and pourability. Stearic acid or other higher fatty acid mixture or salt further improves physical stability. Use of potassium tripolyphosphate in place of tetrapotassium pyrophosphate reduces formation of crystal growth when the product is subjected to elevated temperatures, such at 100°F.

Description

2 ~ 3 LINEAR VISCO~LASTIC AQUEOUS LIQUID
DBT~RG~NT COMPOSITION, ~SP~CIALLY FOR
AUTOMATIC DISHWASHERS, OR IMPROVED HIGH
TEMPERATURE STABILITY

Field of Invention The ~nvention relate~ to aqueous linear viscoelastie (gel-like) liquid compo~ition~ which are especially useful as automatic dishwasher detergent ¢ompo~ition~.
,~., Backqround of the Inven~ion L~quid automatic dishwa~her detergent compo~itions, both aqueous and nonaqueouo, have recently received muah attention, and the aqueou~ products have achieved commercial popularity.
The aceeptanee and popularity of the liquid formulations as eompared to the more aonventional powder product~
stem~ from the convenienee and performanee of the liquid product~. However, even the be~t of the eurrently ava~lable liquid formulations still suffer from two ma~or problems, product pha~e in~tability and bottle residue, and to some extent cup leakage from the dispenser eup of the automatie dishwashing ~machine.

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2~3~23 Representative patent art in thi~ area include~ Rek, U.S. Patent 4,556,504; Bush, et al., U.S. Patent 4,226,736;
Ulrich, U.S. Patent 4,431,559; Sabatelli, U.S. Patent 4,147,650;
Paucot, U.S. Patent 4,079,015; Leikhem, U.S. Patent 4,116,849;
Milora, U.S. Patent 4,521,332; Jones, U.S. Patent 4,597,889;
Heile, U.S. Patent 4,512,908; Laitem, U.S. Patent 4,753,748;
Sabatelli, U.S. Patent 3,579,4~5; Hynam, U.S. Patent 3,684,722.
Other patents relating to thickened aqueous detergent compositions include U.S. Patent 3,985,~68 U.K. Patent Applications G~ 2,116,199A and GB 240,450A; U.S. Patent 4,511,487; U.S. Patent 4,752,409 (Drapier, et al.); U.S. Patent 4,801,395 (Drapier, et al.); U.S. Patent 4,836,946 (Dixit); U.S.
Patent 4,889,653 (Ahmed, et al.). Commonly a~signed co-pending patents include, for example, Serial No. 427,912 filed October 24, 1989; Serial No. 924,385, filed October 29, 1986; Serial No.
323,138, filed Marah 13, 1989; Serial No. 328,716, filed March 27, 1989; Serial No. 323,137, filed March 13, 1989; Serial No.
323,134, filed March 13, 1989.
The solubilizing effect of pota~sium ~alts on 30dium tripolyphosphate in aqueous detergent compositions i~ described in U.S. Patent 3,720,621 (Smeets~. Thi~ patent de~cribes homogeneous liquid composition~ containing 14 to 35 percent ~odium tripolyphosphate, 0.1 to 50 percent of potassium and/or ammonium salt of an inorganic or organic acid, water, and optional ~urfactant~, ~olubilizing agent, organic eequestering agent, per-compound, and other adjuvant~. Potassium pyrophosphate (T~PP) is dieclosed ae the preferred potassium salt for its ~equestering and solubilizing actlvity and al~o because "it effectively stabilizes the tripolyphosphate agent hydroly~is in aqueous ~olution into sodium pyropho~phate and ~odium '- .-' . , ','''.. : : . . , ', '''', -, ' J ~ 2 ~ ~ .'3 ~3 i~

orthophosphate." Th~ patent al~o ~tate~ that, "[t]he content [of TKPP] ~hould not ... be too great 80 as to undergo a double-decomposition reaction with TPP to form ~odlum pyrophosphate, which is well ~nown, has a very low solubility in water and, therefore, tends to ~eparate out as a precipitate. The applicants investigations have ~hown that the optimum proportion of potas~ium pyrophosphate incorporated ~n the liquid detergent compoqitions ... i~ between 5 and Z5 percent based on the TPP
present in the compositions."
U.S. Patent 4,836,948 discloses a vi~coela~tic gel detergent composition characterized by its viscoeity under low and high shear conditions, pH, and steady ~tate viscoelastic deformation compliance. The composition requires the presence of a polycarboxylate polymeric thickener, preferably a cross-linked polyacrylic acid. The compos~tions of this patent also, however, require a trivalent metal conta~ning material, especially an aluminum containing material ~uch as alumina. ~he compo~itions may further include a structuring chelant which may be a salt of carbonate, pyrophosphate or mixture thereof, and preferably the pota~sium salts.
The recently issued V.S. Patent 4,859,358 discloses the incorporation of metal salts of long chain hydroxy fatty acids, a6 anti-tarnishing agents, in thickened aqueous automatic dishwashing detergent compositions. The thickeners for these compositions may be a high molecular weight polycarboxylate polymer, such as those sold under the Carbopol trade name, and specific 600 and 900 ~eries resin~ are mentioned. It is also disclosed that the compositions may include entrained gas, e.g.
air, bubbles to further ~nsure stability. Amounts of air in the range o~ from about 1% to about 20%, preferably from about 5 to .. ..
.. . . , : .: ,: .
. :; . , 15~ by volume will lower the specific gravity of the overall composition to within from about ~ more than to about 10~ le~
than, preferably from 1% more thnn to 5% les~ than, the specific gravity of the aqueous phase. In Example III of this patent, the ~pecific gravity of the composition wa~ ~tated a~ 1.32 g/cm3.
The compositions are not described a~ being linear vi~coelastic and as exemplified do not include any potassium salts.
While the compositions disclosed in our prior application Serial No. 353,712 provided a satisfactory ~olution lo to the problems of phase instability and bottle residu~, as well as cup leaknge, it has now been found that under ~ome storage/handling conditions and/or processing condition~, additional imp~ovements would be desirable. Specifically, if the viscoelastic composition is subjected to repeated heating and cooling cycles, growth of crystals and product thinning and/or precipitate formation has been ob~erved. Chemical analysi~ of the precipitated crystal~ has shown that these cryetals are comprised predominantly of sodium pyrophosphate. In addition, it appears that the crystals tend to become entangled with the polymeric thickener which tendency i~ presumed to account for the thinning out or aqueous phase separation which has been observed in conjunction with crystal formation and precipitation.
Another problem which has been encountered in the preparation of the linear viscoelastic gel formulations of our prior application involved the manner by which the preferred Carbopol thickener is added to water. Specifically, if in forming the slurry of the Carbopol type thickener, the water temperature is maintained at ambient temperature conditions, e.g.
60-80F, the polymer tend~ to be only incompletely hydrated, i.e. results in formation of fish eye~.

., , ., ' . ' ' . . . , . ! ' ,~ 2l~

AB a re~ult of these problems, the finished product not only may be perceived as unaesthetic but, more importantly, the roduct ViBCo8ity iB often lowered which in turn may lead to cup leakage and corresponding degradation in cleaning performance.
It ha~ also been discovered that there is an important relationship between the pH of the composition at each ~tage uring processing and product stability, including both phase separation and loss of viscosity.
The presQnt invention provides iDgredient and processing modification~ to our previously developed compositions which help to alleviate and overcome the above problem~.

Brief De~criPt~on of the ~rawinas Figures 1-6 are rheograms, plotting elasti~ modulus G' and viscous modulus G" as a functlon of applied strain, for the compositions of Example 1, Formulatlons A, ~, C, D, E and F, respectively.

Summar~ of tha Invention According to the present invention there is provided an improved aqueou~ liquid automatic dishwasher detergent composition. The composition is characterized not only by its linear viscoelastic behavior, substantially indefinite ~tability against phase separation or settling of dissolved or suspended particle~ under high and low temperature conditions, low levels of bott}e re~idue, relatlvely high bulk den~lty, and sub~tantial absence of loosely bound water,but also by itB overall product con3istency from batch to batch and run to run and over a wide range of storage and aging conditions, including superior ' . .' . ', '' , ' . " " '' .,:' . ' ' ~ 3 ~ 3 aesthetics, freedom from fish-eye~, absenoe of crystal formation and growth, and resietance to cup leakage.
The present invention was accomplished based, in part, on the diecovery that by repla¢ing part or ~11 of the tetrapotassium pyrophosphate (T~PP) with potas~ium tripolyphosphate (K~PP), cry~tal growth can be inhibited and product consi~tency can be improved and the linear viscoelastic propertie~ can be extended beyond that previou31y achieved.
Further improvements are obtained by utilizing more highly cross-linked and branched, temperature stable and bleach and ~alt compatible polymeric thickening agent~. Furthermore, by controlling the condition~ of mixing the ingredients of the compoeitions, 'and particularly the pH and temperature of the aqueou~ phase used to form the aqueous ~olution of the polymeric thickener, formation of fish-eyes and elimination of viscosity reductions with time can be achieved.
Accordingly, in one aspect the present invention provides an improved linear viscoelastic aqueous liquid automatic ¦di~hwasher detergent composition compri~ing water, up to about 2%
by weight of long chain fatty acid or salt thereof, from about 0.1 to 5% by weight of low-foam~ng chlorine bleaoh stable, water dispereible automatic diehwaeher non-~oap organ~a detergent, from about 10 to 35% by weight of alkali metal detergent builder salt, at lea~t 50~ by weight of which i8 potas~ium tripolyphosphate and at least about 5~ by weight of which is eodium tripolypho~phate, from about 3 to 20~ by weight of a chlorine bleach compound, and a crose-linked polyaarboxylate thickening agent having a molecular weight of at least about 500,000, wherein the aqueous pha~e include~ both sodium and potas~ium ions at a K/Na weight ratio of from about 1/1 to about , : .. . -: ; . .
' . ' .,'' : . .'.,-.
, . , . - .: .. ..

~ ~3~2 45/1. The aompositions preferably have a bulk density of from about 1.28 g/cm3 to about 1.42 g/cm3.
In a preferred embodiment, the linear vi~coela~tic aqueous li~uid automatic dishwasher detergent comprise~, approximately, by weight, (a)(i) 8 to 25% pota~ium tripolyphosphate detergent builder, . (ii~ 2 to 10% sodium tripolyphosphate detergent builder, at an (i)/(ii) weight ratio of from about 1.4/1 to :
10/1;
(b) 5 to 15~ alkali metal silicate;
(c) 1 to 6% alkali metal hydroxide;
(d) b.1 to 3% chlorine bleach stable, water-dispersible organic detergent active material;
(e) 0.05 to 1.5% chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine;
~ g) 0.4 to 1.5~ hydrophilic crose-linked water insoluble polycarboxylate thickening agent having a molecular weight of from 800,000 to 4,000,000 to provide said linear viscoela~tic property;
(h) 0.08 to 0.4% of long chain fatty acid or a metal salt of a long chain fatty acid as a physical stabilizer to increa~e the physical stability of the composition;
~ i) 0 to 10% of a non-cross-linked polyacrylic aaid having a molecular weight in the range of from about 800 to 200,000; and .
(j) water;

! ' ~ ~3~ .3 and wherein in the entire compo~itlon, the ratio, by weight, of pota~sium and sodium iB from about 1.05/1 to 3/1.
In another aspect of the invention, ~ method for preparing the aqueou~ linear vi~coela~tic composition iB
provided. According to this aspect, the method compri~e~ the step~ of I. (a) fully hydrating the cro~s-linked polycarboxylate thickener by slowly adding the thicksner to heated water while moderately agitating the mixture, (b) ~lowly adding a neutralizing amount of cau~tic ~oda to the mixture from (a) while continuing agitation to obtain a disper~ion of the neutralized thickener;
II. ~c) forming an aqueou~ mixture of ~urface active agent~;
~d) heating the mixture in (¢) to a temperature higher than that of the heated water in ~a) and mixing until a homogeneou~ ~mooth premix i8 obtained;
III. (e) uniformly mixing alkali metal builder ~alt~
with the dispersion (b), (f) uniformly mixing the heated premix (d) with the mixture (e), (g) cooling the mixture (f) to a temperature above the temperature of the heated water in ~tep (a), and (h) adding bleach to the mixture (g).
In a preferred embodiment of the lnvention proces~, the pH of the aqueous slurry of the cross-linked polycarboxylate thickener after the neutralization in ~tep (b) and in each 6ucceeding ~tep is maintained at a value of at lea~t 11.

. .. . . . . . .
' . . . . .
- .. - - .' . ' . . .. ' ~ 2 ~

Detailed De6cription and Preferred Embodiments The compo~ition~ of this ~nvention are thickened aqueou~ liquids containing various cleansing active ingredients, detergent builder ~alt~ and other detergent adjuvants, gtructuring and thickening agents and etabilizing components, although some ingredisnt~ may serve more than one of these.
functions.
The advantageou~ characteristics of the compositions of this invention, include physical ~tability, as manifested by little or no phase separation, solid settling or vi~cosity changes over time or resulting from exposure to low or high temperatures, low bottle residue, low cup leakage, high cleaning performance, e'.g. low spotting and filming, dirt residue removal, and consistency in product characteristic~.and performance, and superior aesthetics. These characteri~tics are believed to be attributed to several interrelated factore such a~ low solid~, i.e. undissolved particulate content, product den~ity and linear viscoelastic rheology. ~hese factors are, ln turn, dependent on several critical c.ompositional components and processing conditions of the formulations, namely, (1) the inclusion of a thickening effective amount of a temperature, bleach and salt stable cros~-linked polymeric thickening agent having high water absorption capacity, exemplified by cross-linked polyacrylic : acid, (2) inclusion of a physical stabilizing amount of a long chain fatty acid or salt thereof, and (3) potassium ion to sodium ion weight ratio K/Na in the range of from about 1:1 to 45:1, especially from 1:1 to 3:1, and preferably also (4)-(6): (4) a product bulk density of at least about 1.28 g/cc, especially at least 1.32 g/cc, (5) hydrating the cross-linked polymeric thickener with heated water, and (6) maintainlng the pH of the . , .- - , ,' . . .
. . , :. -.. . . . . . :
.. . . - ... . . ~ .. : . - , -~ 3;3 ~ r~

eutralized polymeric thickener at a p~ of at least 11, referably at lea~t 11.5.
In particular, the linear viscoelastic aqueous liquid utomatic dishwasher detergent compositions of thi~ invention ill, at least in the preferred embodiments, satiafy each of the ollowing stability criteria over the aging temperature-time chedule shown by the following Table As - TABLE A
ging Temperature Duration (F) ~Weeksl Minimum Prsferred 140 ~ 1 ~ 2 120 ~ 6 ~ 8 100 ~ 13 ~ 16 Ambient ' ~ 24 >> 24 More ~pecifically, the compoeitions are aonsidered stable if each f the following stability criteria is satiefied for at least the inimum number of weeks for each aging tsmperature shown in Table s . no visible phase separation (i~e. no solid/liquid separation) . no ~ignificant change (e.g. less than 10%) in iscosities, yield stress or other dynamic-mechanical properties . no crystal growth under repeated heating-cooling ycles over a temperature range of at least 7F to 140F
. no deaolorization or signif~cant color change.
In addition to the above stabillty crlteria, the oompositLons of this inventlon are further characterized by their low bottle residue. Specifically, for the preferred cross-linked polyacrylic acid thickened compositions of this invention, bottle residue~, under the usual use conditions, will be no more than :. . . . .
, -.. . . . .

~ 3 bout 6 to 8~, preferably no more than about 4 to 5%, of the riginal bottle contente, on a weight basis.
~he polymeric thickening agents contribute to the inear viscoelastic rheology of the invention compo~itions. A~
sed herein, ~linear viscoela~tic~ or "linear viflcoelasticity"
ean6 that the elastic (storage) moduli (G') and the viscous 1OB8) moduli (G") are both substantially independent of strain, t least in an applied strain range of from 0-50~, and preferably ver an applied strain ~ange of from 0 to 80%. More pecifically, a compoBition iB considered to be linear iscoelastic for purposes of this invention, if over the strain ange of 0-50~ the elastic moduli G' has a minimum value of 100 ynes/sq.cm., prefsrably at least 250 dynes/sq.cm., and varies es~ than about 500 dyne~/~g.cm., preferably les~ than 300 ynes/~.cm., especially prefera~ly less than 100 dynes/sq.cm.
referably, the minimum value of G' and maximum variation of G' pplies over the strain range of 0 to 80%. Typically, the ariation in 1088 moduli G~ will be le~e th~n that of G'. As a urther characteristic of the preferred linear viscoelastic ompo~itions the ratio of G"/G' (tan ~) is less than 1, referably less than 0.8, but mors than 0.05, preferably more han 0.2, at lea~t over the strain range of 0 to 50%, and referably over the strain range of 0 to 80%. It should be noted n this regard that % ~train is shear strain xlO0.
By way of further explanat~on, the elastic (storage) modulus G' iB a measure of the energy stored and retrieved when a train iB applied to the composition while viscous (1088) modulus " is a measure of the amount of energy dissipated as heat when train is applied. Therefore, a value of tAn ~, 0.05 ~ tan ~

203.~23 preferably 0.2 ~ tan~S ~.8 means that the composition~ wLll retain ~ufficient energy when a stress or strain i8 applied, at lea~t over the extent expected to be encountered for products of this type, for example, when poured from or 6haken ln the bottle, or stored in the dishwasher detergent dispenser cup of an automatic dishwashing machine, to return to itB previous condition when the stress or strain i8 .
removed. The compositions with tan ~ values in these ranges, therefore, will also have a high cohesive property, namely, when a shear or strain is applied to a portion of the composition to cause it to flow, the ~urrounding portion~ will follow. AB a re~ult of this'cohesiveness of the linear vl~coelastic characteristic, the ¢ompositions will rea~ily flow uniformly and homogeneou~ly from a bottle when the bottle i~ tilted, thereby contributing to the physical (pha~e) stability of the formulation and the low bottle residue (low product 108~ in the bottle) which characterizes the invention composition~. The linear vi~coelastic property also contributes to ~mproved phy~ical st~bility again~t phase separation of any undis~olved suspended particles by providing a resi~tance to movement of the particle~
due to the 6train exerted by a particle on the surrounding fluid medium. ~inear vi~coela~ticity also contributes to the elimination of dripping of the contents when the product iB
poured from a bottle and hence reduction of formation of drops around the container mouth at the conclusion of pourlng the product from a container.
A1BO contributing to the physical ~tability and low bottle residue of the invention compo~itions iB the high potassium to sodium ion ratio~ in the range of 1~1 to 45:1, . . . ' . . . ..
': ' ' ' .~ .

preferably 1:1 to 4sl, especially preferably from 1.05:1 to 3:1, for example 1.1:1, 1.2:1, l.S:l, 2:1, or 2.5:1. At these ratios the- solubillty of the solid salt componente, such a~ detergent builder ~alts, bleach, alkali metal ~ilicates, and the like, i8 substantially increaaed since the preeence of the potassium (K+) ions requires less water of hydration than the sodium ~Na+~ ions, such that more water is available to di~solve these salt compounds. Therefore, all or nearly all of the normally solid component~ are present dissolved in the aqueous phase. Since there is none or only a very low percentage, i.e. less than 5~, preferably less than 3~ by weight, of suspended solids present in the formulation there is no or only reduced tendency for undissolved pa~ticles to settle out of the composition~ causing, for example, formation of hard masses of particles, which could result in high bottle residue~ (i.e. loee of product).
Furthermore, ~ny undissolved eolids tend to be present in extremely small particle sizes, ueually colloidal or sub-colloidal, euch ae 1 micron or lese, thereby further reducing the tendency for the undissolved particles to eettle. Since there are ~ubstantially no undiesolved eolid particles of size in excess of 1 micron, the invention products tend to be transparent or at least translucent, depending, in part, on air bubble content.
A still further attribute of the invention compositions contributing to the overall product stability and low bottle residue i~ the high water absorption capacity of the cros~-linked polyacrylictacid-type thickening agent. AB a result of this high water absorption capacity virtually all of the aqueous vehicle component appear~ to be held tightly bound to the polymer matrix.
Therefore, there appears to be no or ~ubstantially no free water ' '.' . '. :. .' .

. J '~ ~38~2~

present in the invention compositions. Thi~ apparent ab~ence of free water (as well a~ the cohe~iveness of the compo~ition) i8 manifested by the ob~ervation that when the compoBition i8 poured from a bottle onto a piece of water ab~orbent filter paper virtually no water i~ absorbed onto the filter paper over a period of at least sQveral hours or longer ~nd, furthermore, the mass of the linear vi~coelastic material poured onto the filter paper will retain its shape and structurs. A~ a result of the absence of loosely bound water, there i~ virtually no phase separation between the aqueou~ pha~e and the polymeric matrix or di~olved solid particle~. This characteri~tic i~ manifested by the fact that when the sub~ect compo~itions are ~ub~ected to centrifugation, e.g. at 1000 rpm for 30 minutes, there is no pha~e separation and the composition remains homogeneous. The preferred composltions have remalned stable for periods in excess of 6 months and more.
In our ~arlier applicatlon Serial No. 07/353,712, it was stated that to maximize physical (pha~e) stability, the density of the composition should be controlled such that the bulk den~ity of the liquid phase i8 approximately the same as the bulk density of the entire compo~ition, including the polymeric hickening agent. Thi~ control and equalization of the densitie~
as achieved, according to our earlier invention, by providing the composition with a bulk density of at least 1.32 g/cc. A
density of about 1.42 g/cc i8 e~sentially equivalent to zero air content.
It i8 important to note that the bulk density of the product can be adjusted by ¢ontrolling the degree of aeration, as well as total solid content. Further, the di~per~ed air bubble~
also contribute to the vi~coela~tic property of the product.

. . . ' . ' , . . ' . , . !. , ,', . ' ' ' '''" ' " '.. "''' ' :'" ' '.;.. ' ' "' " ,' .

~ Ji~ 3 However, it has now been found that alr bubble incorporation i~ not required to achisve atabilization and, in fact, we have been able to prepare ~table thickened product~ with densities a~ low a~ 1.28 g/cc. At den~itie~ below about 1.28 S c/g, however, the flowability of the product tend~ to be degraded and the large air bubble content tends to cause the componition to be too highly tran~lucent or cloudy to opaque.
Therefore, the product density i~ preferably selected in the range of 1.28 to 1.42 g/cc, especially 1.32 to 1.40 g/cc, and most preferably from 1.35 to 1.40 g/cc. Within these range~ air bubble incorporation is determined to achieve the desired product aesthetic appearance and flow characteristic~.
It h~s previously been found in connection with other types of thickened aqueous liquid, automatic di~hwasher detergent compositions that agglomeration or escape of incorporated air bubbles could be avoided by incorporating certain surface active ingredients, especially higher fat~y acids and the salts thereof, such as stearic acid, behenic acid, palmitic acid, sodium stearate, aluminum stearate, and the like.
Therefore, in the present invention, in order to avoid stabilization of air bubble~ which may become incorporated into the compositions during normal proces~ing, ~uch as during various mixing 6teps, i~ avoided by po~t-adding the eurface active ingredients to the remainder of the composition, under low shear condition~ using mixing devices de~igned to minimize cavitation and vortex formation.
A~ will be described in greater detail below the surface aative lngredient~ present in the composition will include the main deteryent surface active oleaning agent, and will al~o preferably include anti-foaming agent (e.g. phosphate ~3~j ester) and higher fatty acid or salt thereof a~ a physical stabilizer.
Exemplary of the polycarboxylate type thickening agent~
are cross-linked polyacrylic acid-type thickening agents eold by B.F. Goodrich under their Carbopol trademark, including both the 900 serie~ re~in~, e~pecially Carbopol 941, which iB the mo~t ion-in~ensitive of this cla6s of polymers, and Carbopol 940 and Carbopol 934, and the 600 series resine, e~pecially Carbopol 614.
The Carbopol 900 series resins are hydrophllia high molecular weight, cross-linked linear acrylic acid polymers having an average equivalent weight of 76, and the general structure illustrated by the following formula:

~ C--C~

HO O n.
Carbopol 941 ha~ a molecular weight of about 1,250,000; Carbopol 940 a molecular weight of approximately 4,000,000 and Carbopol 934 a molecular weight of approximately 3,000,000. The Carbopol 900 series re~ins are cross-linked with polyalkenyl polyether, e.g. about 1~ of a polyallyl ether of ~ucrose havlng an average of about 5.8 allyl groups for each molecule of ~ucrose. The reparation of this cla~s of cro~s-linked carboxylic polymer~ i~
escribed in U.S. Patent 2,798,053, the di~closure of which i~
incorporated by reference. Further detailed information on the Carbopol 900 seriee resins i~ available from B.F. Goodrich, see, for example, the B.F. Goodrich catalog GC-67, Carbopo ~ Water Soluble Resins.
In general, these thickening re~ins are preferably copolymer~ of a water disper~ible copolymer of an alpha-beta .: ... - ... .. .. :
,.', ., ~;'' ',' ..',, '', '.. ''.' ,..
. ' : , . '.: ' ~ 3 monoethylenically un~aturated lower aliphatic carboxylic acid cross-linked with a polyether of a polyol ~elected from oligo saccharide~, reduced derivatives thereof in which the carbonyl group iB converted to an alcohol group and pentaerythritol, the hydroxyl groups of the polyol which are modified being etherified with allyl group~, there being preferably st least two such allyl groups per molecule.
The~e water-di6per~ible cross-linked thickening resins as described in the aforementioned U.S. Patent 2,798,053 and which have been commercialized by B.F. Goodrich a~ the Carbopol 900 series re~ins are prepared from essentially linear copolymer~. More recently, B.F. Goodrich has introduced the Carbopol 600 series resin. ~he~e are high molecular weight, non-linear polyacrylic acid croe~-linked with polyalkenyl ether. In addition to the non-linear or branched nature of these resin~, they are also believed to be more highly crc~s-linked than the 900 serie~ resins ant have molecular weights between about 1,000,000 and 4,000,000.
Mo~t e~pecially useful of the Carbopol 600 series re~ins i~ Carbopol 614 which i8 the most chlorine bleach ~table of this cla~ of thickening re~ln~. Carbopol 614 is aleo highly stable in the high alkalinity environment of the preferred liquid automatic di~hwa~her detergent compositions and i~ also highly stable to any anticipated ~torage temperature conditions from below freezing to elevated temperatures a~ high a~ 120F, preferably 140F, and e~pecially 160F, for period~ of as long as several days to several week~ or month~ or longer.
While the mo~t favorable results have now been achieved with Carbopol 614 polyacrylic resin, other linear or branched cross-linked polycarboxylate-type thicken~ng agents can al~o be ~ 2 ~

used in the composition~ of this invention. A~ u~ed herein "polycarboxylate-type" refers to water-soluble carboxyvinyl polymers of alpha,beta monoethylenically un~aturated lower aliphatic carboxylic acids, which may be llnear or non-linear, and are exemplified by homopolymers of acrylic acid or methacrylic acid or water-di~persible or water-soluble salts, esters or amide~ thereof, or water-soluble copolymers of these acid~ or their salts, ester~ or amides with each other or with one or more other ethylenically unsaturated monomers, such a~, for example, styrene, maleic acid, maleic anhydride, 2-hydroxyethylacrylate, acrylonitrile, vinyl acetate, ethylene, propylene, and the like, and which have molecular weights of from about 500,000 ~o 10,000,000 and are cross-linked or interpolymerized with a multi-vinyl or multl-allylic functionalized cross-llnking agent, especially with a polyalkenyl ether of a polyhydric compound.
These homopolymers or copolymers are characterized by their high molecular weight, in the range of from about 500,000 to 10,000,000, preferably 750,000 to 5,000,000, especially from about 1,000,000 to 4,000,000, and by their water solubility, generally at least to an extent of up to about 5~ by weight, or more, in water at 25C.
These thickening agents are used in their cross-linked . form wherein the cross-linking may be accomplished by means known in the polymer arts, as by irradiation, or, preferably, by the incorporation into the monomer mixture to be polymerized of known chemical cross-linking monomeric agents, typically polyunsaturated (e.g. diethylenically unsaturated) monomers, such as, for example, divinylbenzene, divinylether of diethylene glycol, N,N'-methylene-bisacrylamide, polyalkenylpolyethers (such : . . .. . .
.
. .. .. . -.. , . . : -~ ~ ~ 3 !' ~ r) ',~

as de~cribed above), and the like. Typically, amounts of cros~-linking agent to be incorporated in the final polymer may range from about 0.01 to about 5 percent, preferably from about 0.05 to about 2 percent, and especially, preferably from about 0.1 to about 1.5 percent, by weight of cross-linking agent to weight of total polymer. Gen~rally, tho~e ~killed in the art will recognize that the degree of cro~-llnking ~hould be sufficient to impart some coiling of the otherwi~e generally linear or non linear polymeric compound while maintaining the cro~s-linked polymer at least water disper~ible and highly water-swellable in an ionic aqueous medium.
The amount of the high molecular weight, cross-linked polyacrylic acid or other high molecular weight, hydrophilic cros~-linked polycarboxylate thickening agent to ~mpart the desired rheologlcal property of linear vlscoelasticity will generally be in the range of from about 0.1 to 2~, preferably from about 0.2 to 1.4%, by weight, based on the weight of the composition, although the amount will depend on the particular cross-linking agent, ionic strength of the compo~Ltion, hydroxyl donors and the like.
The compositions of this invention must include sufficient amount of potassium ions and ~odium ions to provide a weight ratio of K/Na of at lea~t 1:1, preferably from 1:1 to 45:1, especially from about 1:1 to 4~1, more preferably from 1.05:1 to 3:1, such as 1.1:1, 1.2:1, 1.5:1, or 2:1. When the K/Na ratio i~ less than 1 there 18 insufficient ~olubllity of the normally solid ingredients whereas when the K/Na ratio iB more than 45, especially when it is greater than about 3 or 4, the product becomes too liguid and phase ~eparation begins to occur.
When the K/Na ratios become much larger than 45, such as in an . - . ' ' .

r most y p~ta~ni~m formulatlon, the polycarboxylate ¦thickener loses it ab~orption capacity and begin~ to salt out of the aqueou~ phase.
The potassium and sodium ions will be made present in ¦the compositlons a~ the alkali metal cation of the detergent builder ~alt( B ) ~ aB well as alkali metal silicate or alkali metal hydroxide components of the compo~itions. The alkali metal cation may also be present in the composition~ as a component of ¦anionic detergent, bleach or other ionlzable salt compound ¦additive, e.g. alkali metal carbonate. In determining the K/Na ¦weight ratios all of these sources ~hould be taken into ¦consideration.
¦ Spec~fic examples of detergent builder salt~ include ¦the polyphosphates, such a~ alkali metal pyrophosphate, alkali ¦metal tripolyphosphate, alkali metal metaphosphate, and the like, ¦for example, ~odium or potassium tripolyphosphate (hydrated or ¦anhydrous), tetrasodium or tetrapotassium pyrophosphate, sodium 10r potassium hexa-metaphosphate, trisodium or tripotassium ¦orthophosphate and the like, sodium or potassium carbonate, ¦sodium or potas~ium citrate, sodium or potassium ¦nitrilotriacetate, and the like.
¦ In accordance with the present invention, however, the ¦detergent builder salts will be compri~ed of mixtures of at least potassium tripolyphosphate (KTPP) and ~odium tripolyphosphate (NaTPP) (e~pecially hexahydrate). Typical ratios of KTPP to NaTPP are from about 1.4:1 to lOsl, e~pecially from about 2:1 to 8:1. The total amount of detergent bullder salts is preferably from about 10 to 35~ by weight, more preferably from about 15 to 35%, especially from about 18 to 30~ by weight of the composition. Of this total amount of the detergent builders at .:, . .. . . .. , ~ ,,.. ,'.; ,: ,. i ., ' ~ 3 lea6t 50~ by weight (preferably at least about 8~ by weight of the composition3 will be KTPP and preferably at least 5~ by we.Lght (preferably at lea~t 2~ by weight of the composition) will be NaTPP. More preferably, the alkali metal detergent builder salt will be comprised of from about 65 to 95~ of RTPP, especially 75 to 90% of KTPP and from about 5 to 35%, e~peoially 10 to 25% of NaTPP. In terms of the total compo~ition, the amount of KTPP will be in the range of from about 8 to 25%, preferably 15 to 22% by weight, and the amount of NaTPP will be in the range of from about ~ to 10%, preferably 3 to 8~ by weight.
When other alkali metal detergent builder ~alts are present in the'formulation, they will usually be pre~ent in amounts less than 5~ by welght based on thq total composition and, in any ca~e, in amounts to maintain the X/Na ratios to within the above described range, preferably from 1:1.1 to 1:3.
The linear viscoelastic composition~ of thi~ invention may, and preferably will, contain a small, but stabilizing effective amount of a long chain fatty acid or monovalent or polyvalent salt thereof. Although the manner by which the fatty acid or salt contributes to the rheology and stability of the compo~ition has not been fully elucidated it iB hypothesized that it may function as a hydrogen bonding agent or cross-linking agent for the polymeric thickener.
~5 The preferred long chain fatty acids are the higher aliphatic fatty aoids having from about 10 to 50 carbon atom~, more preferably from about 12 to 40 carbon atoms, and especially preferably from about 14 to 40 carbon atoms, inclusive of the carbon atom of the carboxyl group of the fatty acid. The aliphatic radical may be saturated or unsaturated and may be 2 ~

straight or branched. Straight chain saturated fatty acids are preferred. Mixture~ of fatty acids may be used, such as tho~e derived from natural ~ource~, such as tallow fatty acid, coco fatty acid, soya fatty acid, etc., or from synthetic sources available from industrial manufacturing processes.
Thu~, examples of the fatty acids include, for example, decanoic acid, dodecanoic acid, palmitic acid, myri~tic acid, ~tearic acid, behenic acid, oleic acid, eicosanoic acid, 'allow fatty acid, coco fatty acid, soya fatty acid, mixture~ of these acid~, etc. Stearic acid and mixed fatty acid~, e.g. stearic acid/palmitic acid, are preferred.
It has, however, also recently been discovered by some of U8 and othe~s that further improvements in phase stability, particularly under elevated temperature storage conditions, and maintenance of product viscosity levels can be obtained by using longer chain length fatty acids in the range of from Clg to C40.
Either individual or mixture~ of these longer ahain length fatty acids can be used, however, the average chain length should be in the range of from about 20 to 32 carbon atoms, especially 24 to 30 carbon atoms and mixture of fatty acids encompassing this range are preferred. Sultable mixed fatty ac~ds are commeraially available, for instance those sold under the trade name Syncrowax by Croda.
When the free acid form of the fatty acid is used directly it will generally associate with the potassium and sodium ions in the aqueous phase to form the corresponding alkali metal fatty acid soap. However, the fatty acid salts may be direatly added to the composition as sodium salt or potassium salt, or as a polyvalent metal salt, although the alkali metal salts of the fatty acids are preferred fatty acid salts.

" ''' ' , '- ' :- ' - , The preferred polyvalent metals are the di- and tri-valent metals of Groups IIA, II~ and III~, such as magnesium, calcium, aluminum and zinc, although other polyvalent metals, including those of GroupB IIIA, IVA, VA, IB, IVB, VB, VI~, VIIB
and VIII of the Periodic Table of the Elements can also be used.
Specific examples of such other polyvalent metals include Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, etc. Generally, the metal~ may be present in the divalent to pentavalent state.
Preferably, the metal ~alts are used in their higher oxidation ~tates. Naturally, for use in automatic dishwashers, as well a~
any other applications where the invention compo~ition will or may come into contact with article~ used for the handling, storage or ser~ing of food products or which otherwise may come into contact with or be consumed by people or animals, the metal salt should be selected by taking into consideration the toxicity of the metal. For this purpose, the alkall metal and calcium and magnenium salts are especially higher preferred a8 generally safe food additives.
The amount of the fatty acid or fatty acid salt stabilizer to achieve the desired enhancement of physical stability will depend on such factors as tha nature of the fatty cid or its salt, the nature and amount of the thickening agent, etergent active compound, inorganic salts, other ingredients, as ell as the anticipated storage and shipping conditions.
Generally, however, amounts of the fatty acid or fatty acid salt stabilizing agente in the range of from about 0.02 to 2%, preferably 0.04 to 1%, more preferably from about 0.06 to 0.8%, especially preferably from about 0.08 to 0.4%, provide a long term stability and ab~ence of phase separation upon standing . ,.. . . . . - - :
.
:' ' ' "," :" - ' ' ' ' '' .'' ~ Q~

or during transport at both low and elevated temperatures as are required for a commercially acceptable product.
Depending on the amounte, proport~one and types of fatty acid phy~ical stabilizers and polycarboxylate thickening agent#, the addition of the fatty acid or ealt not only increases physical etability but also provides a simultaneou~ increase in apparent viscosity. Amounts of fatty acid or salt to polymeric thickening agent in the range of from about 0.08-0.4 weight percent fatty acid salt and from about 0.4-1.5 weight percent polymeric thlckening agent are u~ually euffic~ent to provide these simultaneous benefits and, therefore, the u~e of these ingredients in these amountB i8 moet preferred.
In order to achieve the deeired benefit from the fatty acid or fatty acid ealt stabilizer, without stabil~zation of excess incorporated air bubbles and consequent excessive lowering of the product bulk den~ity, the fatty acid or ealt iB preferably poet-added to the formulation, preferably together with the other surface active ingredients, including detergent active compound and anti-foamLng agent, when present. Theee eurface active ingredients are preferably added ae an emulsion in water wherein the emulsified oily or fatty materiale are finely and homogeneously disper13ed throughout the aqueous phase. To achieve the desired fine emulsification of the fatty acid or fatty acid ealt and other surface active ingredients, it ie usually necessary to heat the emul~ion (or preheat the water) to an elevated temperature near the melting temperature of the fatty acid or its salt. For example, for stearic acid having a melting point of 68-69C, a temperature in the range of between 50C and 70C will be used. For lauric acid (m.p.~47C) an elevated temperature of about 35 to 50C can be used. Apparently, at .;. : ... . . . ' , .

~ 3g~

these elevated temperatures the fatty acid or ~alt and other surface active ingredients can be more readily and uniformly dl~per~ed (emul~ified) in the form of fine droplets throughout the composition.
Foam inhibition i~ important to increase dishwa~her machine efficiency and minimize destabilizing effects which might occur due to the pre~ence of exces~ foam within the washer during use. Foam may be reduced by suitable selection of the type and/or amount of detergent active material, the main foa~-producing component. The degree of foam i~ also somewhat dependent on the hardne~s of the wash water in the machine whereby ~uitable adjustment of the proport~ons of the builder galts, such as NaTPP which has a water softening effect, may aid in providing a degree of foam inhibltion. However, it is generally preferred to include a chlorine bleaah stable foam depre~sant or inhibitor. Particularly effective are the alkyl phosphoric acid e8ters of the formula O

and especially the alkyl acid phosphate esters of the formula HO P---OR
OR
In the above formulas, one or both R groups in each type of ester may represent independently a C12-C20 alkyl group. The ethoxylated derivative~ of each type of ester, for example, the condensation products of one mole of e~ter with from 1 to 10 mole~, preferably 2 to 6 moles, more preferably 3 or 4 moles, ethylene oxide can al80 be used. Some examples of the foregoing ~ J

are commercially available, such a~ the products SAP from Hooker and LPKN-158 from Rnapsack. Mixture~ of the two types, or any other chlorine blea¢h etable types, or mixture~ of mono- and di-e~ters of the ~ame type, may be employed. E~pecially preferred in a mixture of mono- and di-C15-C18 a}kyl ac~d pho~phate e~ter~
such as monostearyl/distearyl acid phosphate~ 1.2/l, and the 3 to 4 mole ethylene oxide aondensates thereof. When employed, proportions of 0.05 to 1.5 weight percent, preferably 0.1 to 0.5 weight percent, of foam depressant in the composition is typical, the weight ratio of detergent active component (d~ to foam dep-essant (e) generally ranging from about 10:1 to 1:1 and preferably about 5:1 to 1:1. Other defoamers which may be used include, for ~xample, the known silicones, such as available from Dow Chemicals. In addition, it i~ an advantageous feature of this ~nvention that many of the stabilizing salts, such as the stearate salts, for example, aluminum etearate, when included, are also effective as foam killers.
Although any chlorine bleach compound may be employed in the compositions of this invention, such as dichloro-i~ocyanurate, dichloro-dimethyl hydantoin, or chlorinated TSP, alkali metal or alkaline earth metal, e.g. potassium, lithium, magnesium and especially sodium, hypochlorite is preferred. The compo~ition should contain sufficient amount of chlorine bleach compound to provide about 0.2 to 4.0% by weight of available chlorine, as determined, for example, by acidification of 100 parts of the composition with excess hydrochloric acid. A
~olution containing about 0.2 to 4.0~ by weight of sodium hypoahlorite contain~ 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 hypo-:. . . :
: ::

chlorite (NaOCl) 80Iution of from about 11 to about 13~a~ailable chlorine in amounts of about 3 to 20%, preferably about 7 to 12~, can be advantageously used.
Another surprising and unexpeeted benef it and advantage of the preferred Carbopol thiekened eompo~itions of thi~
invention is the essentially total masking of any chlorine bleach odor which i8 eharacteristic of, for example, the prior known clay thickened produet~. By virtue of the masking of chlorine bleach odor, it has been found that the ~ubjeet eompositions can be blended with ~ubstantially lower amounts of fragranee, e.g.
lemon oil fragranee, to aehieve the same or superior olfaetory sensation for the consumer. For instanee, as little as 0.05~ of lemon fragrance will have the ~ame effect as about 0.12% in clay thiekened produets.
Furthermore, the addition of fragranee does not adversely affeet the stability criteria, as previously defined, such a~ viscosity or phase ~tability, of the compo~itions.
Detergent active material useful herein ~hould be low-foaming and stable in the presence of ehlorine bleaah, when pre~ent, especially hypoehlorite bleaeh, and for thi~ purpose those of the organic anionie, nonionic, amine oxide, phosphine oxide, sulphoxide or betaine water dispersible surfaetant types are preferred, the first mentioned anionies being most preferred.
Partieularly preferred ~urfaetants herein are the linear or branched alkali metal mono- and/or di-(Cg-C14) alkyl diphenyl oxide mono- and/or di-sulphates, eommereially available for example as DOWFAX (registered trademark) 3B-2 and DOWFAX 2A-l.
In addition, the surfactant should be eompatible with the other ingredient6 of the composition. Other suitable organic anionic, : ;: ' . . '".' ',' ' - . '.. ' - ~ 2~3~

on-soap surfactants include the primary alkylsulphate~, alkylsulphonate~, alkylarylsulphonates and sec.-alkylsulphates. Examples include sod~um Clo-Clg lkyl6ulphates such as sodium dodecylsulphate and sodium tallow 5 lcoholsulphate; sodium Clo-Clg alkanesulphonates such as sodium exadecyl-l-~ulphonate and sodium C12-Clg alkylbenzenesulphonate~
such as ~odium dodecylbenzenesulphonates. The corresponding otas~ium salts may also be employed.
AB other sultable surfactants or detergents, the amine xide surfactants are typically of the structure R2RlN0, in hich each R represents a lower alkyl group, for instance, ethyl, and Rl repre~ents a long chain alkyl group having from 8 o 22 carbon a~oms, for instance a lauryl, myristyl, palmityl or etyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R2RlP0 or sulphoxide RRlS0 can be mployed. Betaine surfactant~ are typi¢ally of the structure 2RlN~R"C00-, in which each R repre~ent~ a lower alkylene group having from 1 to 5 carbon atoms. Specific examples of these surfactants include lauryl-dimethylamine oxide, myri~tyl-dimethylamine oxide, the corre~ponding phosphine oxides andsulphoxide~, and the corresponding betaine~, including dodecyldimethylammonium acetate, tetradecyldiethylammonium pentanoate, hexadecyldimethylammonium hexanoate and the like.
For biodegradability, the alkyl groups in these surfactants should be linear, and such compounds are preferred.
Surfactant~ of the foregoing type, all well known in the art, are describedr for example, in U.S. Patents 3,985,668 and 4,271,030. If chlorine bleach is not u~ed than any of the well known low-foaming nonionic surfactants such as alkoxylated . , :, .~ . .'. . '. ,: .' .

~ ~ 2~3~ 3 fatty alcohols, e.g. mixed ethylene oxide-propylene oxide condensate~ of C8-C22 fatty alcohols can also be u~ed.
The chlor~ne bleach stable, water disper~ible organic detergent-active material ~surfactant) will normally be pre~ent in the composition in minor amounts, generally about 1~ by weight of the composition, although smaller or larger amount~, such a~
up to about 5%, such as from 0.1 to 5%, preferably from 0.3 or 0.4 to 2% by weight of the composition~ may be used.
Alkali metal (e.g. potassium or sodium) silicate, which provides alkalinity and protection of hard surfaces, such as fine china glaze and pattern, i8 generally employed in an amount ranging from about 5 to 20 weight percent, preferably about 5 to 15 weight perdent, more preferably 8 to 12% in the composition.
The sodium or potassium silicate i~ generally added in the form of an aqueous solution, preferably having Na20sSiO2 or ~20:SiO2 ratio of about 1:1.3 to 1:2.8, especially preferably 1:2.0 to 1:2.6. At this point, it ehould be mentioned that many of the other components of this compositlon, especially alkali metal hydroxide and bleach, are also often added in the form of a preliminary prepared aqueous dispersion or solution. However, unles~ otherwise noted, when amount3 of a particular ingredient are given, the reference iB to an active ingredient basis, i.e.
does not include the aqueous carrier.
In addition to the detergent active surfactant, foam inhibitor, alkali metal silicate corrosion inhibitor, and detergent builder salt~, which all contribute to the cleaning performance, it is also known that the effectiveness of the liquid automatic dishwasher detergent compo~itions is related to the alkalinity, and particularly to moderate to high alkalinity levels. Acaordingly, the compositions of this invention will ~ '- 21~3~

have pH values of at least about 9.5, preferably at least about 11 to as high as 14, generally up to about 13 or more, and, when added to the aqueoua wash bath at a typical concentration level of about 10 grams per liter, will provide a p~ in the wash bath of at least about 9, preferably at least about lOt such as 10.5, 11, 11.5 or 12 or more.
The alkalinity will be achieved, in part, by ths alkali metal ion~ contributed by the alkali metal detergent builder ~altc, e.g. sodium tripolyphosphate, potassium tripolyphosphate, and alkali metal silicate, however, it i8 usually necessary to include alkali metal hydroxide, e.g. NaOH or ROH, to achieve the desired high alkallnity. Amounts of alkal~ metal hydroxide in the ranqe of from about 0.5 to 8%, preferably from 1 to 6~, more preferably from about 1.2 to 4%, by weight of the compo~ition will be sufficient to achieve the desired pH level and/or to adjust the K/Na weight ratio.
While as stated above, high alkalinity is desired with regard to improved cleaning performance, it has now additionally been discovered that the pH of the composition during processing is highly important for product stability, e.g. viscosity, and bleach stability and phase stability. Specifically, it has been found that, e~pecially for the Carbopol clsss of thickening agents, the amount of basic neutralizing agent, preferably NaOH, should be sufficient to provide the neutralized thickening agent with a pH of at least 11, preferably at lea~t 11.5. Furthermore, these high alkallnity level~ should be mslnts~ned throughout the product formulation steps, namely, the pH value of at lea~t 11, preferably at least 11.5, should be maintained during the successive additions of the other ingrediente of the composition.

~ 3 AB will be shown by the examples given below, if the pH
rop~ to a lower value, there 18 a 10~8 in vi~cosity, a~ well as stability (as manifested by liqu~d phRse separation) over time.
Other alkali metal ~alt~, ~uah a~ alkali metal carbonate may also be present ~n the composition~ ln minor amounts, for example from O to 4%, preferably O to 2%, by weight of the composition.
Another often beneficial additive for the pre6ent liquid automatic dishwasher detergent compo~itions is a relatively low molecular weight, non-crosslinked polyacrylic acid or neutralized with cau~tic, such a8 the commercial product Acrysol LMM-45N, which has a molecular welght of about 4,500.
The low m.w. polyacrylic acids can provide additional thickening characteristics but are primarily introduced for their ability to function as a builder or chelating agent. In this capacity, the low m.w. polyacrylic acids can aontribute to reduced spotting or streaking and reduced filming on di~hes, glas~ware, pots, pans, and other utensil~ and appliances.
Generally, a suitable molecular weight ranges for the non-cros~linked polyacrylic acid 18 from nbout 800 to 200,000, preferably 1000 to 150,000, especially from about 2,000 to 100,000. When present in the formulat~on, the non-crosslinked polyacrylic acid can be used in amounts up to about 10% by weight, preferably from about 1 to 8% by weigbt, especially 2 to 6% by weight of the composition.
Other conventional ingredients may be ~ncluded in these compositions in small amounts, generally les~ than about 3 weight percent, ~uch as perfume, hydrotropic agents such as the sodium benzene, toluene, xylene and cumene ~ulphonAtes, preservatives, dyestuffs and pigments and the like, all of course being stable ;'" . ," '.'. '. ' '''. ' ", , '. .

o chlorine bleach compound and high alkalinity. E~pecially referred for coloring ara the chlorinated phthalocyaninea and olysulph~de~ of alumino~ilicate which provide, respectively, lea~ing green and blue tint~. To achieve ~table yellow colored roducts, the bleach stable mixed dyes C.I. Direct Yellow 28 (C.I. 19555) or C.I. Direct Yellow 29 (C.I. 195S6) can be added o the compositions. These colors meet stability criteria escribed in Table A. Tio2 may be employed for whitening or eutralizing off-shades.
Although for the reasons previously discu~ed excessive ir bubbles are not often desirable in the invention ompositions, depending on the amounte of di~olved solids and liquid phase densitie~, incorporation of small amount~ of finely divided air bubbles, generally up to about 10% by volume, preferably up to about 4% by volume, more preferably up to about 2~ by volume, can be incorporated to adjust the visual appearance, product density and flowability. The incorporated air bubbles should be finely divided, such as up to about 100 ¦microns in diameter, preferably from abou~ 20 to about 40 microns in diameter. Other inert gases can also be used, such as nitrogen, carbon dioxide, helium, oxygen, etc.
The amount of water contained in the~e compositions should, of course, be neither 80 high as to produce unduly low viscosity and fluidity, nor 80 low as to produce unduly high vis¢osity and low flowability, linear viscoelastic properties in either oase being diminished or de~troyed by increasing tan 1. Such amount is readily determined by routine experimentation in any particular instance, and generally will range from 30 to 5 weight percent, preferably about 35 to 65 weight percent.
Preferably, the watex should also be deionized or softened.

., ' , ' "..' -- .', .

. 2 ~

The manner of formulating the invention componitions i8 l~o important. AB di~cu~ed above, the order of mixing the ngredient~ a~ well as the manner in which the mixing iB
erformed will generally have a signiflcAnt effect on the roperties of the composition, and in particular on product ensity, (by incorporation of more or less air), viscosity and hysical ~tability (e.g. phase separation). Thus, according to he preferred practice of this invention the compositions are repared by forming a di~persion of the polycarboxylate type hickener in heated water, e.g. 35 to 60C (95 to 140F), referably 40~ to 50C (104 to 122F), under moderate to high shear conditions, neutralizing the di~solved polymer to a pH of t least 11, preferably at least 11.5, such a~ from 11.5 to 13.0, to cau6e gelation. After transferring the thickener dispersion to a main mixing tank processing 1B continued by introducing, while continuing mixing, the detergent builder salts, alkali jmetal silicatee, chlorine bleach compound and remaining detergent additive~, including any previously unu~ed alkali metal hydroxide, if any, other than the surface-active compounds. All of the additional ingredient~ can be added simultaneously or ~equentially. Preferably, the ingredient~ are added sequentially, with mixing continued for from 2 to 10 minute~ for each ingredient, although it iB not neces~ary to complete the addit~on of one ingredient before beginning to add the next ingredient. Furthermore, one or more of the~e ingredient~ can be divided into portions and added at different times. These mixing steps should al~o be performed under moderate to high shear rates to achieve complete and uniform mixing. These additional ingredient mixing eteps may be carried out at room temperature, but preferably the elevated temperature of the thickener ~lurry ; : '. . ' - ' . ' ' :

2038~2~
i8 maintained. The compo~ition may be allowed to age, if neces~ary, to cause dissolved or di~persed air to dis~ipate out of the composition.
The remaining surface active ingredients, including the anti-foaming agent, organic detergent compound, and fatty acid or fatty acid salt stabilizer is post-added to the previou~ly formed mixture in the form of an aqueous emulsion (using from about 1 to 10%, preferably from about 2 to 4% of the total water added to the composition other than water added a~ carrier for other ingredients or water of hydration) which is pre-heated to a temperature in the range of from about Tm-5 to Tm+20, preferably from about ~m to Tm+10, where ~m is the melting point temperature of the fatty acid or fatty acid salt. For the stearic acid ~tabilizer the heating temperature is in the range of 150 to 170F ~65 to 77C). For the high chain length fatty acid~ and mixtures Cl~-C36, correspondingly higher temperatures may be used, such as from about 160 to 200F ~ca. 70 to 95C).
However, if care i8 taken to avoid excessive air bubble incorporation during the gelation step or during the mixing of the detergent builder salts and other additives, for example, by operating under vacuum, or using low shearing conditions, or special mixing apparatus, etc., the order of addition of the surface active ingredients should be less important.
In accordance with an especially preferred embodiment, the thickened linear viscoelastic aqueous automatic dishwasher detergent composition of this invent~on ~nclude~, on a weight basis:
(a)(i) 8 to 25%, preferably 10 to 20%, potassium ripolyphosphate detergent builder;

- - 20~2~ ~

(ii) 2 to 10~, preferably 4 to 8%, sodium ripolypho~phate detergent builder, at an (i)/(ii) weight ratio f from about 1.4/1 to 10/1, preferably 2/1 to 6/1;
(b) 5 to 15, preferably 8 to 12%, alkali metal silicate;
(c) 1 to 6%, preferably 1.2 to 4%, alkali metal ydroxide;
(d) 0.1 to 3%, preferably 0.5 to 2%, chlorine bleach ~table, water-disper~ible, low-foaming organic detergent active material, preferably non-soap anionic detergent;
(e) 0.05 to 1.5%, preferably 0.1 to 0.5%, chlorine bleach stable foam depressant;
(f~chlorine bleach compound in an amount to provide about 0.2 to 4%, preferably 0.8 to 1.6%, of available chlorine;
(g) non-linear, water-di~persible polyacrylic acid thickening agent comprising at least one high molecular weight hydrophilic polycarboxylate having a molecular weight of from 750,000 to 4,000,000, preferably 800,000 to 3,000,000, in an amount to provide a linear vi~coelasticity to the formulation, referably from about 0.2 to 2%, e~pecially preferably from about 0.4 to 1.5%, more preferably from about 0.4 to 1.0%;
(h) a long chain fatty acid or a metal ~alt of a long hain fatty acid in an amount effective to Lncrease the phy~ical ~tability of the aompositions, preferably from 0.08 to 0.4%, more preferably from 0.1 to 0.3%; and (i) 0 to 10%, preferably 1 to 8~, especially 2 to 6%
of non-cros~linked polyacrylic acid having a molecular weight in the range of from about 8Q0 to 200,000, preferably 1000 to 150,000, especially 2,000 to 100,000; and : ' , ',. , ~' . .

- 2 ~ 2 ~

(j) balance water, preferably from about 30 to 75%, ore preferably from about 35 to 65%; and wherein in the entire omposition the ratio, by weight, of potassium ion~ to ~odium OIIB iB from about 1.05/1 to 3/1 or 4/1, preferably from 1.1/1 to 2.5/1. The composltions may also have an amount of air ncorporated therein such that the bulk density of the omposition is from about 1.28 to 1.42 g/c¢, preferably from bout 1.32 to 1.42 g/cc, more preferably from about 1.35 to 1.40 /cc.
The compositions will be supplied to the consumer in suitable di~penser containers preferably formed of molded lastic, e~pecially polyolefin plastic, and most preferably paque or tra~slucent polyethylene, for which the invention ompositions appear to have particularly favorable ~lip characteri~tice. In addition to their linear viscoelastic character, the compositions of thi~ invention may also be characterized a~ pseudoplastic gels (non-thixotropic) which are typically near the borderline between liquid and solid viscoelastic gel, depending, for example, on the amount of the olymeric thickener. The invention composition~ can be readily oured from their containers without any shaking or squeezing, i.e. have a sufficiently low yield stress value to flow under their own weight (gravity), although squeezable containers are often convenient and accepted by the consumer for gel-like product~.
The liquid aqueous linear viscoelastic automatic i~hwa~her composition~ of this invention are readily employed in known manner for washing dishes, other kitchen utensils and the like in an automatic di~hwasher, provided with a suitable ¦¦dotergent dL~ en~er, ln an aqueou~ waoh bath conta1n1ng an - . : ., . ., .:-.. . . . .

'- 2~3~

ffective amount of the compo~ition, generally sufflcient to fill r partially fill the automatic dispenser cup of the particular achine being used.
The invention also provides a method for cleaning ishware in an automatic dishwashing machine with an aqueou~
a~h bath containing an effective amount of the liquid linear iscoelastic automatic dishwa~her detergent composition as escribed above. The composition can be readily poured from the olyethylene container with little or no squeezing or ~haking into the dispensing cup of the automatic dishwashing machine and will be sufficiently viscous and cohesive to-remain ~ec~rely within the dispensing cup until ~hear forces are again applied thereto, such'a~ by the water ~pray from the di~hwa~hing machine.
The invention may be put into practice in varioue way~
and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying examples.
All amounts and proportions referred to herein are by ¦weight of the compo~ition unle~s otherwise indicated.
¦Exam~le 1 The following formulations A-F were prepared a~
escribed below:

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, ~ 1~' ~ ~r ~ l o~ In 1~
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f~ a~ u~ _l In ~ a~ ,1 -ol ,, o m c l o l ~r N _1 l _1 O -I l~ ~ l . I¢ o~ ~r _1 1~') ~ _~ _1 ~`I _l l . .. . . . . ..... . . .
! ': ', . . . , - ' ' . . ~ ' . ' . . , ' ' .

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m. 1~ ~ ~ g I I I
1~ ~ ~r ~r ~ Z
t.q u~ u~ u~ ul o ¦ OD 3 !~ l ¦ H

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il ~

a,~ 1_ ~ 3 Pl m I o ~1 a~ ~ l l ~-I ~ ~ un~0 1, , ., ",. , . . ' .,' ' '.' ~: ' :.' ,,, " : , . ~.. :, . :, . .

'- 2 ~ i Formulations A, B, C, D, E and F are prepared by fir~t forming a uniform di~per~ion of the Carbopol 614 or 940 thickener in about 97% of the water of the total formula water. The Carbopol is slowly added by sprinkling it into the vortex of previously colored deionized water preheated to a temperature of 105F u~ing a mixer equipped with a premier blade, with agitation set at a medium shear rate, a~ recommended by the manufacturer.
After mixing for about 15 minutes, the dispersion i~ then neutralized by addition, under the ~ame mixing, of the cau~tic ~oda (50% NaOH) componsnt until a thickened product of gel-like con~istency is formed ~about 10 minutes).
To the resulting gelled dispers~on the silicate, sodium tripolypho~phate (NaTPP), tetrapota~sium pyrophosphate (TKPP), or pota~sium tripolyphosphate (KTPP), the surfactant emulsion ~described below) and bleach and ¢olor, are added ~equentially, in the order stated, with the mixing continued at medium shear for several minutes before adding the next ingredient. After the addition of the surfactant emulsion ~at 160F), the mixture i~
cooled to from 90-95F before the bleach i~ added.
Separately, the surfactant emulsion of the phosphate anti-foaming agent (LPKN), ~teario acid or fatty acid mixture and etergent (Dowfax 3B2) is prepared b~ adding the~e ingredients to the remaining 3~ of water and heating the resulting mixture to a temperature in the range of 160~ (71C). In formulation E, the ~cry601 LMM 45-N may be added at this stage.
The rheograms for the formulations A, ~, C, D, ~ and F
are ~hown in figures 1-6, respectively.
These rheograms are obtained with the System 4 Rheometer from Rheometrics eguipped with a Flu~d Servo with a 100 grams-centimeter torque transducer and a 50 millimeter parallel ~ 40 2 ~ 2 ~

late geometry having an 0.8 millimeter gap between plates. All easurements are made at room temperature (25~1C) in a humidity hamber after a 5 minute or 10 minute holding per~od of the eample in the gap. The measurements are made by applying a frequency of 10 radians per second.
All of the compo~ition formulations C, D and F exhibit linear viscoelasticity as seen from the rheograms of figure 2-6.
No phase separation at from ambient temperature to 140F were ob~erved for any of the formulations for at least the minimum number of week~ required to satisfy the criteria ~tability as shown in Table A above. Formulations E and F were still being tested when this application was filed.
However, in the control formulations A and B maintained at 100F, the TKPP crystallized in the aqueous phase and eventually formed ~ufficiently large size crystal~ which separated to the bottom of the composition. Also, as seen in figures 1 and 2 formulatione A and B are not linear vi~coela~tic, at leaet within the preferred criteria a~ previously described.
Formulations C, D, E and F, according to the invention did not ndergo any crystal growth.
For the bottle residue test, each formulation is llowed to age for about 1 week at amb~ent temperature in a standard 32 ounce small necked polyethylene bottle. An amount of roduct is poured from the bottle to fill a standard ~ized i~pen~er cup of an automatic di~hwasher. The bottle is then replaced in an upright position and i~ retained in the upr~ght position for at least 15 minutes. This procedure of filling the diffpen~er cup, placing the container in the upright position and waiting at least 15 minutes is repeated until no more product . . . . ...
'.' , .''. ,' '-. . ~3~^3~2~

low~ from the bottle. At thi~ time, the weight o~ the bottle i~
easured. Bottle residue iB calculated a Wf x100 Wo 5 O i8 the initial weight of the filled bottle and ~f iB the final eight of the filled bottle. The bottle renidue for each formulation A-F i8 about 4 to 5%. ~ormulations C-F have i~co~itie~ of from 10,000 to 20,000 mea~ured with a Brookfield LVT viscometer, ~4 spindle at 20 rpm mea~ured at 80F. all of he~e product~ are ea~ily pourable from the polyethylene bottle.
ExamPle 2 A Carbopol 614 ~lurry i~ formed a~ described in Example 1 except that,the coloring agent i~ fir~t added to the deionized ater (about 92% of the total added water) and the amount~ of the ingredient~ are changed a~ shown below. The premix (~urfactant emul~ion) of the surface actlve ingredients is al~o formed as in Example 1 using stearic acid a~ the fatty acid stabilizer and the remaining 8% of the total added water.
The ingredient~ are then mixed together with the Carbopol 614 ~lurry in the following order~ alkali metal silicate, NaTPP (powder), RTPP (powder), ~urfaatant emulsion, bleach and perfume. The reHulting compo~ition i~ obtained with the following ingredient~ in the following amounts:
Inaredient Amount (wt%~
eionized Water q.~.l00 arbopol 614 1.00 aOH (38~Na2O~ 6.38 Na ~ilicate (1:24)(47.5S) 20.83 KTPP (anhydrou~)powder 20.35 aTPP (3% H2O)powder 5.26 owfax 3B2 0.80 LPRN 0.16 Stearic Acid 0.15 ~leach (Na hypochlorite-13%) 9.23 CI Pigment Green 7 (CI 74260) 0.0024 Highlights (fragrance) 0.05 .: ' ,: ' . . , 203go2~ ~

The compoBition has a pH of 11-3 ~ 0.2 and density (~p.gr.) of 1.39 + 0.03. The vlsco~ity at 80F measured with a Brookfield LVT viscometer at 20 rpm with a #4 spindle i~
12,000 + 2,000.
S All of the preferred criterla as set forth in Table A
above are sati~fied.

' ' ' ' .. ' . . ,, ., .: -. . . .. -

Claims (18)

1. A linear viscoelastic aqueous liquid automatic dishwasher detergent composition comprising water, up to about

2% by weight of long chain fatty acid or salt thereof, from about 0.1 to 5% by weight of low-foaming chlorine bleach stable, water dispersible automatic dishwasher non-soap organic detergent, from about 5 to 40% by weight of alkali metal detergent builder salt, at least about 50% by weight of which is potassium tripolyphosphate, up to about 20% by weight of a chlorine bleach compound, and cross-linked polycarboxylate-type thickening agent having a molecular weight of at least about 800,000 wherein the aqueous phase includes both sodium and potassium ions at a K/Na weight ratio of from about l/l to about 45/1.
2. The composition of claim 1 wherein the long chain fatty acid or salt thereof is present in an amount of from about 0.01 to 0.8% by weight.

3. The composition of claim 1 which further comprises an alkali metal silicate anti-corrosion agent.

4. The composition of claim 1 which further comprises up to about 2% by volume, based on the total volume of the composition, of air in the form of finely dispersed bubbles.

5. The composition of claim 1 wherein said polycarboxylate-type thickening agent is a cross-linked polyacrylic acid having a molecular weight in the range of from about 1,000,000 to about 4,000,000.

6. The composition of claim 5 wherein the cross-linked polyacrylic acid thickening agent is present in an amount of from about 0.1 to 2% by weight of the composition.

7. The composition of claim 1 wherein the K/Na ratio is from about 1/1 to about 3/1.

8. The composition of claim 1 which further comprises an anti-foaming agent.

9. The composition of Claim 1, said composition satisfying the following stability criteria for at least 24 weeks at ambient temperature and for at least 1 week at 140°F:
substantially no phase separation, substantially no change in dynamic-mechanical properties, no crystal growth, and no significant color change.

10. A linear viecoslastic aqueous liquid automatic dishwasher detergent comprising, approximately by weight, (a)'(i) 8 to 25% potassium tripolyphosphate detergent builder, (ii) 2 to 10% sodium tripolyphosphate detergent builder;
(b) 5 to 15% alkali metal silicate;
(c) 1 to 6% alkali metal hydroxide (d) 0.1 to 3% chlorine bleach stable, water-dispersible organic detergent active material;
(e) 0.05 to 1.5% chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine;
(g) 0.4 to 2% high molecular weight hydrophilic cross-linked polycarboxylate acid thickening agent to provide said linear viscoelastic property;
(h) 0.01 to 0.4% of long chain fatty acid or a metal salt of a long chain fatty acid as a physical stabilizer to increase the physical stability of the composition;

(i) 0 to 10% of a non-crosslinked polyacrylic acid having a molecule weight of from about 800 to 200,000; and (j) water;
and wherein in the entire composition the ratio, by weight, of potassium and sodium is from about 1.05/1 to 3/1, said composition having a bulk density of from about 1.28 g/cc to 1.42 g/cc.

11. The composition of claim 10 which comprises, approximately, by weight, (a)(i) 15 to 22% potassium tripolyphosphate;
(ii) 3 to 8% sodium tripolyphosphate (b) 8 to 12% alkali metal silicate;
(c) 1.2 to 4% alkali metal hydroxide;
(d) 0.5 to 2% chlorine bleach stable, water-dispersible, low-foaming non-soap anionic detergent active material;
(e) 0.1 to 0.5% chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide 0.8 to 1.6% of available chlorine;
(g) 0.4 to 1.0% of cross-linked polyacrylic acid having a molecular weight of from about 1,000,000 to 4,000,000;
(h) 0.08 to 0.3% of stearic acid or a mixture of stearic acid and palmitic acid, or a mixture of fatty acids having from 18 to 36 carbon atoms;
(i) 0 to 8% of a non-crosslinked polyacrylic acid having a molecular weigh of from about 1,000 to 150,000;
(j) water; and (k) air, in the form of finely divided bubbles, in an amount up to 2% by volume, based on the volume of the composition;

and wherein the ratio K/Na in said composition is from 1.1/1 to 2.5/1, said composition having a bulk density in the range of from 1.35 g/cc to 1.40 g/cc.

12. The composition of claim 10 wherein (d) comprises alkali metal mono- and/or di- (C8-C11) alkyl diphenyl oxide mono- and/or di-sulphate.

13. The composition of claim 10 in which the chlorine bleach compound (f) is sodium hypochlorite.

14. The composition of claim 10 in which the foam depressant (a) is an alkyl acid phosphate ester, an alkyl phosphonic acid ester containing one or two C12-20 alkyl groups, an ethoxylated product thereof or a mixture thereof.

15. The composition of Claim 11, said composition satisfying the following stability criteria for at least 24 weeks at ambient temperature and for at least 1 week at 140°F:
substantially no phase separation, substantially no change in dynamic-mechanical properties, no crystal growth, and no significant color change.

16. A method for preparing a thickened stable aqueous automatic detergent dishwashing composition which comprises the steps of I.(a) fully hydrating a cross-linked high molecular weight polycarboxylate thickener by slowly adding the thickener to water preheated to a temperature of from 95 to 140°F while moderately agitating the mixture, (b) slowly adding a neutralizing agent comprising caustic soda to the mixture from (a) while continuing agitation to obtain a dispersion of the neutralized thickener;
II.(c) forming an aqueous mixture of a low-foaming, chlorine-bleach stable, water dispersible surfactant, and optionally one or both of a foam depressant and a fatty acid or fatty acid salt as a stabilizing agent;
(d) heating the mixture in (c) to a temperature higher than 140°F and mixing until a homogeneous smooth surfactant premix emulsion is obtained;
III. (e) uniformly mixing (i) potassium tripolyphosphate and (ii) sodium tripolyphosphate with the dispersion (b) at an (i)/(ii) ratio from 1.4:l to 10:1, (f) uniformly mixing the heated premix surfactant emulsion (d) with the mixture (e), (g) cooling the mixture (f) to about 95°F or lower, and (h) adding bleach to the mixture (g).

17. The method of claim 16 wherein the amount of neutralizing agent is sufficient to raise the pH of the polycarboxylate dispersion to at least 11, and maintaining the pH
at each subsequent step to at least 11.

18. The method of claim 17 wherein the pH is 11.5 or more.