CA1326621C - Automatic dishwashing detergent powder - Google Patents

Abstract

AUTOMATIC DISHWASHING DETERGENT POWDER

Abstract of the Invention A free flowing, stable, water-soluble, powdered automatic dishwashing detergent with superior solubility, handling and storage characteristics is provided. The compositions comprise an inorganic polyphosphate carrier onto which is absorbed a nonionic detergent. The "loaded" carrier is fixed with powdered silicate and the other usual adjuvants such as bleach, pigment, etc. High levels of detergent are possible without adversely affecting the aforementioned advantages and superior characteristics.

Description

AUTOMATIC DISHWAHSING DETERGENT POWDER

The present invention relates to an impro~ed auto-matic dishwashing detergent powder with superior performance solubility, pourability, handling and storage characteristics and me~hod for making and using same.

BACKGROUND OP THE INYENTION AMD PRIOR ART

In general automatic dishwashing detergent powders contain water soluble builder salt, wa~er-soluble silicate, bleach, preferably a wate~soluble chlorine bleaching agent, and water-soluble detergent which is usually an organic, low- i foaming (i.e. low "sudsing'i) ~on-ionic. For best cleaning efficiency and anti-corrosion effects, the compositions are usually formulated with alkaline salts (i.e. sodium and potassium). In the normal environment in the dishwashing machine, the automatic dishwashing compositions generally yleld l~ I a pH in the range of about 9.0 to 12.0 and more generally about 1 3.5 to 11.5. The alkaline bullder salts which have been used (: :
are both of the inorganlc type (e.g. pyrophosphates; carbonates,, ~ silicates and so forth) and Of the organic type e.g. amino-3~ carboxylates such as trisodium nitrilotriacetate, tetrasodlum f ethylene diamlne tetra-acetate, sodium citrate, sodium itaconate~
sod~lum polymaleate, sodium inter pol~maleates, such as maleic-acrylic (or vlnyI) interpolymers, sodium oxydlsuccinate~and 1, ;
so forth. ~ ~
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~ 32662 1 The builder generally function to increase the clean-ing action of the composition by supplying alkalinity and also by removing (i.e. "sequestering") ions which affect the action and efflciency of the organic detergent.
The silicates which have been used are those wherein the Na20:SiO2 ratio varies from 2:1 to 1:4 and more generally from about 1:1 to about 1:3.4, typically 1:1, 1:2 and 1:2.4.
The hleach employed is generally a chlorlne-yielding agent and has been used in varying amounts but generally to give ava:ilable chlorine levels of from abou~ 0.3% to about 10%
and, more often, levels of about 1% to 5%. Typical bleaches are the inorganic types such as sodium, lithium and calcium hypochlorite, and chlorinated trisodium phosphate9 as well as the organic forms such as the cli- and tri- chlorocyanuric acids and their alkali (e.g. sodium alnd potassium~ metal salts, N-chloracetyl urea, 1,3-dichloro-5,5-dimethylkydantion, etc.
The nonionic detergents in common usage have been any of the conventional hydrophobe mo~eties (e.g. C8 to C20 alcohols, phenols, amides, acids, etc.~ reacted with ethylene oxide (or mixtures ~ith other oxyalkylating agents such as propylene oxide or butylene oxide). Typical nonionics used hav~
been n-dodecanol with 10 moles of ethylene oxide; tetradecyl alcohol-hexadecyl alcohol (1:1 welght ratio) with 5, 10, 15 or 20 moles af ethylene oxlde; polyo~ypropylenes condensed (i.e.
termina~ed) with oxyethylene groups and having the ge~eral ormula H~(C2H4)x(C3H6~y(C2H4) H wherein y= 5 to 100 and typically 10 or 15 and x ~ay be from about 5 to several hundred : ~ ., I .
e.g. 10, 20, 40, 509 etc. Among the latter type of nonionics have been those where the oxyethylene component comprlses from :~
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1 32~621 about 15% to 90% on a weight basis of the non-ionic. Types of non-ionic detergent disclosed as generally useful in auto-matic dishwashing compositions can be found in U.S. Patents 3314~91, 3~5~207, 2677700, 2979528, 3036118, 3382176, 4115308 and 4411810. It has been known and generally described that non-lonic surfactants even though a preferred class of detergents because of their low-foam characteristics, are not, generally, considered "bleach-s~able" detergents and where the latter is of importance use of anionic surfactant, albeit higher foamers, has been reported. IllustratiT~e and a discussion of this pro-blem can be found in U.S. Pat~nts 4116844, 5005027 and 4235732.
Automatic dishwashing detergents have been provided in two basic forms 9 as powders and as "liquids" (or semi-liquids or pastes). The powders represent the "first generation'l~.
They are simple to formulate, easy to dlspense from machlnes which have, in the main , been designed to handle powders and ¦~ not liquids; and because of tke presence of the formulat$on ~ "actives" in solld state, (and usually the components comprise i separate and discrete particles), there is a minlmum of inter-I; action among the co~posi~ion ingredients. "Liquids,~' the so-i called "second generation" of products in this area , on the ¦ other hand, are more convenient to dispense from ~he package;

3 also they are generally more soluble in water and therefore have ~ less te~dency to remain and/or leave residues in the machine dispenser cup. Phase separation leading to decreased homo-geneity and an exacerbation of component interaction are among some of the minuses oÇ the llquid system. Some of the U.S.
Paten~s mentloned earlier are speciflcally directed to "liquid"
~,~ sy9tems.

., . , ~ 326621 : :
62301-15~0 BRIEF DESCRIPTION OF THE INVENTION
The presen* invention relates to an improved automatic dishwashing de~ergen~ in powder form which is highly efficacious, has superior stability, is phase stable and homogeneous and notwithstanding its powder characteristic has many of the advantages of the liquid systems i.e.
dispensability, pourability and solubility without, however~
the problems and disadvantages often attendiny the use of -liquid automatic dishwashing compositions. --The compositions of this invention comprise builder salt, generally alkaline builder sal~, alkali-metal silicate, non-ionlc surfactant and as a preferred optional ingredient, bleaching agent. The product is characterized by a base bead of builder salt having absorbed thereon the nonionic sur~actant, sald bead belng admixed with the silicate and bleach (where used). Where other optional ma~erials are used they, too, are convenlently post blended with ~he base beads.
These materials may be alkali salts including builder salts anti-oxidants, dyes, pigments, ~ragrances, anti-~oamers, flllers, sequestering agen~s, soil suspendiny agents, dralnage -improvers and ~he like.
ETAILE~ DBSCRIPTION OF ~HE I~VE~TION - ~-The present invention provides a free-$10wing, ;~
automatic dishwashing deter~ent powder composition comprising ~.-~ater-soluble, inorganic, polyphosphate base, non-ionic surfactant carried by said ba~e and admixed therewith powdered water soluble alkall silicate.
The invention further provides a method for making a free-flowing automatlc dishwashing compositlon comprising - -preparing aqueous slurry of water-soluble inorganic phosphate and a minor amount of a polymer, spraying drying to form . "
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1 32~6~1 6~301-1540 , : ~
essentially hollow beads, absorbing thereo~ from ~% to 40% by weight based on the weight o~ the be,ads of a non-ionic .:
surfactant having a melting point belo~ about 150C by spraying said nonionic in liquefied form onto said beads and thereafter dry mlxing said beads with powdered sodium silicate.
The outstanding automatic dishwashing compositions ~hich are provided are powders and comprise a base material on which is absorbad or "loaded" a detergent, and in admixture -therewith an alkaline silicate and any other desired compsnentæ. Of particular value is a bleaching ayent and alkaline react:Lng compounds such aæ alkali carbonates, bicarbonateæ, borates, hydroxlde,s and so forth.
The base material which is the carrier ~or ~he sur~actant is a spray-dried phosphate composition which also con~ains a small amount of a polymeric substance.
The spray-dried base is generally characterized as a ~
"haæe bead" although it may not necessarily ~e a bead in the ~ ;
usual geQmetric form. The absorben~ base material is comprised ~ ~-of a maior portion Q~ inorganic ~alts and generally and prefarably phospha~e material. Suitable phosphates include -~
tris~dium phosphate, sodiu~ tripolyphosphate, monobasic sodium phosphate, dlbaæic sodlum phosphate, dibasic sodlum pyrophosphate, tetra æodium pyruphosphate, sodium -hexametaphosphate and the llke. The corresponding potassium : .
salts along with mixtures of sodium and potassium salts are uae~ul. It may be desira~le to add other salts to the ;
phosphate such a~ the alkali metal carbonates, bicarbonates, borates and silicates. The alkaline earth salts (e.g. calcium, magnesium~ etc.~ o~ the non-phosphate inorganlcs may be used if . . .
~ 30 desired and/or indicated. ~j ~
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. ,~ ~,.. -., ~ ~66~ 62301~1540 In general, the base "bead" i5 prepared by spray-drying a slurry of the phosphate-containing composition. The processing of slurries and spray-drying them to form base beads is ;~
described in U.S. Patent 4414129 to David Joshi. -, - :
The base material will generally comprise irom about ; -50 to 95% alkali-metal polyphosphate. On an anhydrous basis, the base may compxise from about 50% to 99% of inorganic salts -~
and again, preferably alkali metal polyphosphate. Minor amounts of moisture are almost invariably present and the water ~ -content may vary from a fe~ or less percent (e.g. 0.5%, 1%, 2%, 3%) to 20% and more but more generally from about 5% to 15%, typlcally S%, 8%, 10% and 12%.
Other alkaline ~alts, particularly sodium carbonate, sodium tetrabora~e and sodium silicate may be admixed with the phosphate in the crutcher before spray-drying. Generally these - --.. ., - . - .
materials are used in leæs than ma~or amountP, generally from -very ~mall amoun~s e.g. 1%, 2~, 5%~ up to larger quantities, typically 10%, 15%, 20~, 30%, 35% and 40%. Where ~ilicate is u~ed in the crukcher mix lt i5 usually one of lesser alk~linity e.g. Na20:SiO2 ra~io of about 151.6 to 1~3.4 typically 1:2.4. -~
A second component of the base bead is a water soluble polymeric material such as sodium polyacrylate, which ~ -is the most preferred polymer salt. Other water-soluble ~
polymer~ lat lea~t soluble ln such salt form~ as poly (hydroxy) ~-acrylates, copolymeræ and inter polymers of acrylic acid with o~her copolymerizable monomers (usually ~-olefinically unsaturated) such as vinyl pyrrolidone, vinyl acetate, .
hydroliz~d polyvlnyl acetate (75-95% polyvinyl alcohol), ~ acrylamide, methyl vinyl ether and so forth can be used. 0~her i 30 polymer~ include .,,,,~..............

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water-soluble forms of starch and cellulose and particularly derivatives such as sodium carboxy methylcellulose and the like.
Natural proteins are useful, too; examples include gelatin and the llke. In general, the useful materials are characteriz~d by water-solubility and compatibility to form a base carrler sultable for loading the detergent in quant1ties from 1 to about 10% and where described up to quantities of 25-35%.
Such polymers are useful in amounts of from about 0.5% to about 10% and preferably from about 1% to 8~. Typical usage would be 1.5%, 2%, 2.5%, 3~, and 4%, espec$ally with sodium poly-acrylate. The molecular weights of the synthe~ic polymers may vary from several hundred to several mlll~ong e.g. 600; 1200, 2000; 5000; 150,000; 500,000; 1,000,000; 5,000,000 and the like~
After the based bead has been prepared, it is used as an absorbent or carrier for the detergent. The latter are preferably non-ionic surfac~ants which, ln liquld form are sprayed on to the base beads. The more desirable non-ionlc detergent materials are generally pasty to waxy at room temper-ature or at least sprayable as a liquid at somewhat elevatsd temperatures e.g. 30C, 40C, 60DC, 80C and 100C.
The nonionic detergent materials comprise any of the cla~s designated as nonlonic and generally comprises the oxyalhylated derivatives (preferably oxyethyl or mixed oxpropyl-oxye~hyl) of hydrophobic base moieties of about C8 to C3Q carbon content of such functional types as alcohols, thioalcohols, I
esters, acids and amides. The preferred compounds are oxyethy- !
~i lated and mixed oxypropylated-oxyethylated al$phatic alcohols of Clo to C18.

_ 7 1 3~66~

The non-ionic detergents are the preferred types because of their physical characteristics; liquifiable and sprayable as well as low foaming; one of the major character-istics of a detergent which ad~ersely affects the cleaning ef-ficacy of the dishwashing co~position is a high level of foam.
This is due primarily to the fact that the cleaning action is proportional to the force of the jets of ~ater impinging on the dishes, etc., and high levels of foam and thick or dence foam reduce this force and thusly the cleaning action.
A general formula for preferred non-ionics is:
C~3 R ~CH2CH~ OH
wherein R = hydrogen or C10 to C18 alkyl and preferably linear alkyl. Rl is hydrogen or methyl and n = an integer from 20 to 150, preferably 5 to 50 and more preferably 5 to 20.
Where R is hydrogen the oxyalkyl groups are oxypropyl as a hydrophobe backbone with oxyet'hyl or oxye~hyl and oxypropyl terminating groups.
Compounds where R is hydrogen generally have the following formula:
' II.

~,C~ H2CHO '~CH2c~2ot~H , , where m may range from 3 to 50 or more and p and q may range similarly as n in Formula I.
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62301-1540 ~ .
Illustrative compound~ includP:
1) n-tridecanol + 7.EØ *
2~ n-tetradecyl alcohol ~ 8.EØ -3) n-hexadecylalcohol ~ 8.EØ ~:

4) a C12-C14 linear alcohol containing 55% oxyalkyl of which 42% are ethoxy and 58% proproxy in a randon ~.
distributlon.

5~ A C18 alkyl linear alcohol containlng 57% ethylene -;:~
oxide.
C~3 ~:

6) H(~ CH2C~2)s (~CH2cH ) (~H2CH2 )5 Mixed carbon chain length~ are o~ten, and typically, ~-~
uæed since they are very o~ten qui~e readily available as mixtures from both synthetic and natural source~.
The amount of nonionic may range from a few percent up to 35 to 40~ on a welght for weight ~a~is. It ls prefexred to at leaæ~ about 2 or 3 to 4%. Typical a~ounts would be 4%, : :
6%, 8~ and in some embodiments 20%, 25% and 30%. Where high :~
non-ionic loa~lng ls de~lred, then it 1~ preferred to utillze 50me 0~ the formula in organic polypho~phate as ~o~t added ~.
anhydrou~ ~or v~ry low motsture aontent e.g. 1%, 2% or 3%).
-~ .-: In general, while othex inorganic alkaline materialg : ....: .,::
may be ueed in preparlng the non-ionic carrier phosphate bead, lt l~ usually les~ deslrable to U~2 silica~e at lea~t a3 a ..
major replacement for the polymer 1~ not as only a minor r;eplaceDent for the~polymer materials, and the ~llicate where , - . :
~ ~ employed ln thls inveneion ~or its alkalinlty and anti- -: ~ . .
~ : corroslve benefits is best utlllzed a~ a po~t added component. .~

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The silicates which are used in the compositlons of the present invention and particularly those which are post added as powders comprise any of the commercially available alkali silicates available as powders, wherein the Na20 to to SiO2 molar ratio varies from 2:1 to 1:4 and preferably varies from 1:1 to 1:3.5. Typical and most preferred silicates are sodium and potassium silicates where the Na20 to SiO2 molar ra~io varies from 1:1 to 1:205 and especially the metasilicates (1:1 ratio).
The physical form of the particulate silicate may be any form i~e. any density, porosity, shape and particle size. Thus densities may range from a bulk density of 0.3 to one of 1.5 and preferably 0.4 or 0.5 to 0.7 or 0.8, 0.9 or 1Ø
Typical particle sizes for the post added silicates may be a product of 20, 30, 4(), 50, 60 mesh. A commercially available product with 80-85% or more between 40 & 60 mesh i~ very useful. Similarly a produ-t with 84~ between 10 & 65 mesh i9 excellent.
One additional and particularly outstanding char-acteristic and feature of one aspect of the the compositions --of this lnvention is their relative low bulk density as compared to the usual commercial products. Thus for example, while commercial products may have densities of the order of -Q,8 those of the present invention may be made having 20 ~o SO% less density.

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î 326621 52301-15~0 The silicates used may be in the form of beads~
hollow ox otherwise, finely divided powder, regular and ~ -irregular and diverse shaped particles. Particularly preferred silicates ara available as Metsobeads from PQ Corporation and Britesil LD24. Mixtures of any of the foregoing may also, of course, be used.
The amount of ~ilica~e used may vary from a fe~7 percent to a significant and almost ~iajor a~ou~t such as 2%, ~%
and 5% to 10%, 15%, 20%, 30% a~d 40%. Particularly preferred ranges are 5~ to 25% and ~% to 15%.
The op~ional bleach which, however, ls highly desirable and pre~erred can be any of those conven~ionally used : :
in autodish comFio~ition~. The ahlorlne bleaches described :-earlier in ~hei "Background of the Inven~ion and Prlor Art"
section can al~o be used in this in~i~entlon. Similar amount^~
may bei u~ed as e.g. 0.3% to about 10%, preferably 1~ to ~% (by welght)~ In place of chlorine-yielAing ~e.g. OCl ) bleaches, one may use oxygen bleaches such as siodium perbora~e monohydra~e, sodlum perbora~e te~rahydratei/ sodium persul~ate, - -~odium percarbonate and ~o forth. Oxygen bleach levels m~y `:~:
range ~rom about 2% to 40 or 50% and preferably from about 5%
to 30%.
Many other ad~uvants may be added to the present ... .
co~posi~ions ~ithout adversely affecting their utillty and ~ performanae. For exampl~, bacterlocides enzymes, antl-spotting I agents, sheeting agents, gla~e-damage inhibitor~ ~e.~. boric acid anhydride) may be used in amount~ ~rom as ~ tle as 0.01% :
to 10~, 15~ or more.
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The following examples will serve to illustrate the present invention without being deemed limitative ther~of.
Parts, where used, are by weight unless otherwise indicated. -~
E~AMPL~ 1 An aqueous slurry of anhydrous sodium tripolyphosphate powder (TPP~ water and sodium polyacrylate powder is prepared at ~5% solids level handled and spray dried as in E~ample 1 of Joshi U.S. Patent 4414129. Of the spray dried produc~ the TPP comprises 89.55%, ~he polyacrylate 2.45%
and the ~alance of 8% is moisture in the bead. The bead has a specific gravity of 0.5 and has considerable mechanical ... .
strength.
The beads so produced are introduced in~o a rotary -- ;
drum and post prayed with a nonlonic surfactant (liquefied) at ~ -a temperature of 120~F untll 6% by w~ight of the nonionic has been "loaded" on the carrler beads. The non-ionic is a C12-C
.: .....
linear alcohol con~aining about 55~ ~f random oxyethyl and --;
oxypropyl groups (42 wt. % oxyethyl - 58 Wt7 % oxypropyl ~ ~-group~). These groups are introduced into the alcohol u~ing a -,:, :.: -mixed ethylene oxide - propylene oxide stream. Th~ beads a~
the time of spraying are at a te~perature of about 100 to 105F. (38 to 41C). 68~g of the "loaded" beads are then dry m~xed with 125~ of powdered sodium metasilicate (P~ Corporation :. .;, Metsobaad~), 102 grams of anhydrous sodium carbonate and 33g of sodlum dichloroisocyaneva~e dihydrate. - -- .: .:: ..-In u~e in an automatlc dishwasher 37g of the above formulatlon are used (in lieu of 50g of "A" commqrcial autodlsh powder). ~xcellent cleansing is obtained. The spotting and ~ -~llming performance is better than "A' commercial t state of the ax~ powde~.

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EXAMPLE II

Example I ls repeated except that the beads are loaded with 25% by weight of the non-ionic and the composltion is varied somewhat to have the follwing components:
WT. %

Based Beads of Ex. 160.0 Sodium metasllicate*12.0 Sodium carbonate of Ex. 1 10.0 Nonionic of Ex. 1 15.0 Cl. bleach of Ex. 1 3.0 100 . 0 *the metasilicate used here is a high bulk denslty product (50 lbs/ft3) EXAMPLE III

: Example II is repeated except that the amount of base beads is only 50% (and, therefore, non-ionic is only 12.5%)~
~: The addltlonal "hole" of 12.5% in the for~ula is fllled with sodium trlpolyphosphate (anhydrous) which is post mixed and blended into the formula with the metasilicate, carbonate and : bleach.
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: The previous exa~ples a:re repeated using as the non-:ionic ~n each instance7 the followinig:
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(a) C18 linear alcohol containing 57% condensed ethylene oxide, (b) Olin SLF-18-polytergent, (c) n-tetradecylalcohol and 8 mole~ of ethylene oxide.
In preparing the composition of this invention, the usual e~uipment may be used. Examples include Patterson Kelly twin shell blender for batch operation and a Patterson Kelly -Zig-Zag blender for continuous processing.
Tower conditions and operating parameters for -producing the non-ioni~ carrier-beads are fully described in U.9. Patent 4414129.
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Claims (11)

1. A free-flowing, automatic dishwashing detergent powder composition comprising water-soluble, inorganic, polyphosphate base, non-ionic surfactant carried by said base and admixed therewith powdered water-soluble alkali silicate.

2. A composition as defined in claim 1 wherein the polyphosphate base is a spray-dried bead-like product and comprises from about 50 to 95% by weight, the non-ionic from about 2% to 40%
by weight and the silicate from about 2% to 40% by weight.

3. A composition as defined in claim 2 wherein the polyphosphate is sodium tripolyphosphate, the non-ionic is a C10-C18 linear alcohol containing at least 5 moles of condensed ethylene oxide and the silicate is sodium metasilicate.

4. A composition as defined in claim 3 including a water-soluble polymer in the polyphosphate base.

5. A composition as defined in claim 4 wherein the polymer is a polyacrylate and comprises 0.5% to 10% by weight of the composition.

6. A composition as defined in claim 5 including a bleaching agent.

7. A composition as defined in claim 6 wherein the bleaching agent is a chloroisocyanurate or an alkali or calcium hypo-chlorite.

8. A composition as defined in claim 7 including powdered alkaline salts other than polyphosphate.

9. A method for making a free-flowing automatic dishwashing composition comprising preparing aqueous slurry of water-soluble inorganic phosphate and a minor amount of a polymer, spraying drying to form essentially hollow beads, absorbing thereon from 2% to 40% by weight based on the weight of the beads of a non-ionic surfactant having a melting point below about 150°C by spraying said nonionic in liquefied form onto said beads and thereafter dry mixing said beads with powdered sodium silicate.

10. A process as defined in claim 9 wherein a powdered chlorine yielding bleaching agent is dry blended along with the silicate.

11. A method for cleaning dishes and the like in an automatic dishwasher which comprises adding to the dishwasher, preferably to the dispenser means therof, the free-flowing composition of claim 1 and thereafter putting the machine through its normal washing cycle.