AU607535B2

AU607535B2 - Composition suitable for use as, or in, an acidic rinse aid

Info

Publication number: AU607535B2
Application number: AU22314/88A
Authority: AU
Inventors: Paolo Zini
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 1987-09-18
Filing date: 1988-09-16
Publication date: 1991-03-07
Anticipated expiration: 2008-09-16
Also published as: ZA886913B; AU2231488A; EP0308221B1; GB8721936D0; NO884074L; NO884074D0; DE3870560D1; NO172751C; EP0308221A1; NO172751B; CA1314187C; JPH01158098A

Description

COMMONWEALTI- OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICA'TON NAM 'E ADDRESS OF APPLICANT: Rohmn and Haas Company Independence Mall West Philadelphia Pennsylvania 191,05 United States of America This dOCumenCrt contain~s the amendments made unde-r ctzoo and is correct for Priflti-7 a4a00 0 0 00 00a00 o0 0 00 00 00 0 NAME(S) OF INVENTOR(S): Paolo ZINI 0 ADDRESS FOR SERVICE: DAVIES COLLISON 0 00 Patent Attonieys M~ore 00 0 0 0 a I Little Collins SreMlore 00 0 00 00 0 o 00 000 COM:PLETE SPECIFICATION FOR Ti-4E INENTION ENTITLED: 00 0 Composition suitable for use as, or in, an acidic rinse aid 0 0 0 0 000 The following statement is a full description of this invention, includ1ing ine best method of 0 a performing it known to me/us:- 4' ACIDIC RINSE AID" The present invention is concerned with compositions suitable for use as, or in, acidic rinse aids, particularly acidic rinse aids for machine dishwashers. However, the compositions may alpo be suitable for use as, or in, glass cleaning compositions, for example window cleaning compositions, a000 0 0 0metal cleaning compositions, textile production, 000 finishing and wash-off compositions, and water o 0 0 01 treatment compositions, for example in cooling 00 circuits.

0 at Rinse aids are invariably used in commercial and 00 0 0 institutional machine dishwashers and frequently in household dishwashers. A final rinse of fresh water 00 serves to displace pre-final rinse water and its 00o attendant detergent and soil residues. In large 00. commercial machines the final rinse water is normally .0-o introduced at a temperature of 80*C or above; the high 00 ~temperature being used to sanitize as wqelll as to promote rapid flash dirying of tableware, glassware or 0 0::0 p las ticsware (herein collectively referred to as DO.% 1substrate") surfaces as they exit the machine. in some 00.0 00 00 "low ene~rgy" commercial dishwashers the final rinse water may be used at a lower temperature of about 60 0

C,

amd may contain about 50 parts per million (ppm) of a conventional chlorine'-releasing agent for sanitization.

"Sanitization" in household dishwashers is achieved by effective batchwise cleaning with multiple wash and rinse cycles using fresh water.

Rinse aid formulations for machine dishwashers, are conveniently aqueou~s solutions containing a low foamn nonionic surfactant, and may be injected into the final fresh water rinse at a concentration of about $0 to about 300 ppm. The surfactant in the rinse water 2 lowers the surface tension of the rinse water and improves the wetting action of the rinse water on the somewhat hydrophobic substrate surfaces. Improved wetting reduces the tendency of the rinse water to form drops containing dissolved solids on the substrate surface which give rise to spots upon drying.

Accordingly, the functions of the surfactant in the rinse aid are to effectively reduce the surface tension during the draining period and to be low foaming so as to avoid traces of foam on the rinsed substrate which "oo result in a residue upon evaporation.

0000 o In commercial dishwashers, the final rinse 000000 o o water, after having been used to rinse the substrates, 0 a 0 o o will be mixed with the circulated pre-final rinse 00 0 00 00 water. The rinse water may also be fed back into the 00 0 0o 0o wash water or be used directly as the wash water for the next cycle. Consequently, when a rinse aid is 0 00 formulated, the surfactant and any other additive o should be chosen based on their effect in the wash bath 0 00 °o0 o as well as in the rinse water. An additional important aspect of a rinse aid, therefore, is the ability of the rinse aid to defoam food soils in the alkaline wash bath. Proteinaceous food soils are particularly prone 0o 00to foam in agitated alkaline wash baths. Foam, or more 0 0 0 t specifically entrapped air, in the wash spray, will o reduce the mechanical efficiency of the spray and interfere with maximum soil removal. Many low foam surfactants are effective soil defoamers. However, other additives may interfere with soil defoaming.

While low foam surfactants have improved the wetting of rinse water on substrates, they have not completely eliminated spotting and streaking problems.

It is known that the addition of polycarboxylated polymers, such as polyacrylic acid, to the rinse water can further reduce spotting and filming or streaking.

It is believed that these water-soluble polymers can 3 adsorb onto slightly soiled substrates and make the surface more hydrophilic. A more hydrophilic surface can be more readily wetted by the surfactant-containing rinse water. Polycarboxylated polymers are especially useful because they do not contribute to foam formation and do not interfere with the soil defoaming activity of the low foam surfactants. Such polycarboxylated polymers also have the advantage, when used in hard water, that they aid in preventing precipitation of hardness ion salts.

0 A major obstacle, however, exists to the use of o000 polycarboxylated polymers in rinse aids. This obstacle a 0 0o o0 is due to the incompatibility of these polymers in 0 0 0 o e aqueous rinse aid formulations containing low foam 0 0 0 oo 0 surfactants. Combining such polymers and surfactants in 00 0 o ooo water results in phase separation. Upon standing for a short period of time the water containing these 0 oo polymers and surfactants will form two or more layers 0 Q S00° of different compositions. This phase separation is 0 00 ao°oo obviously unsatisfactory since non-uniform addition of 0 o0 the desired components will occur as the formulation is 0 o injected into the machine. For example, the formulation may contain too little surfactant to provide adequate 0 oo wetting or too much leading to excessive foam.

Hydrotropes such as sodium xylene sulfonate, 000000 o s cumene sulfonate and short chain alkyl sulfates have been used to permit the formulation of low foam nonionic surfactants into stable aqueous concentrates.

(See, for example, US-A-3,563,901 and US-A-4,443,270).

These hydrotropes have little effect, however, on compatibilizing low foam surfactants with polycarboxylated polymers in aqueous concentrates.

Moreover, even in cases where hydrotropes give limited compatibility, they suffer from the major disadvantage of interfering with the food soil defoaming activity of the surfactants. Water-miscible solvents, such ae 4 isopropanol and propylene glycol, and hydrogen bond-breaking compounds, such as urea, have also been proposed for use in formulating rinse aids containing low foam nonionic surfactants. However, they have been found to have little or no effect on compatibilizing polycarboxylated polymers with low foam surfactants.

Combinations of a hydrotrope and such solvents offer some improvement over the use of either compound alone, but the combinations still result in rinse aids having limited compatibility and adversely affect food soil c00 C defoaming activity.

0o^e Low molecular weight polyelectrolytes have been o combined with low foam surfactants in powder detergent formulations. US-A-4,203,858 discloses a low foaming, Sphosphate-free, dishwashing composition comprising an oo alkali metal or ammonium carbonate, such as sodium carbonate, a water-soluble salt of a polyelectrolyte o oo having a molecular weight of from about 500 to 4,000, and optionally up to 10 weight percent of a 0 0 0 0 oo foam-suppressing nonionic surfactant. The weight ratio ooo of polyelectrolyte to carbonate ranges from 5:95 to oo 20:80. Typical of the polyelectrolytes are acrylic, methacrylic, maleic and itaconic acid polymers.

o oo Homopolymers and copolymers of acrylic and methacrylic .oo. acid having a molecular weight ranging from 504 to 1291 0000 S are preferred. US-A-4,203,858 discloses that the major differences between this composition and prior poly-lectrolyte-built dishwashing composition, are the low concentration of polyelectrolyte and the poor metal ion sequestering capability of these polyelectrolytes.

Other references disclosing (meth)acrylic acid polymers and their salts in detergent and cleaning applications include US-A-3,671,440; 3,853,981; 3,950,260; 3,933,673; 3,922,230 and 4,521,332. None of these references, however, address or offer solutions for polyelectrolytes with low foam surfactants in rinse aid concentrates.

The desired nature of a rinse aid is dependent upon the hardness of the water used in the dishwashing machine. In the case of soft water which has a low level of hardness, e.g. below about 10 French degrees of hardness, the rinse aid conveniently has a pH of 7 or above (herein referred to as an alkaline rinse aid), and, in the case of hard water which has a high level of hardness, e.g. above about 30 French degrees of hardness, the rinse aid conveniently has a pH of less than 7 (herein referred to as an acidic rinse aid). In the case of alkaline rinse aids the problem of o compatibilizing low foam nonionic surfactants with 0I 0 go 0o polycarboxylated polymers has been overcome, and stable o a alkaline rinse aids have been produced, by using, as r0 0 oa compatibilizer or stabilizer, high molecular weight 0O 0 °oo° copolymer formed from monomers comprising methacrylic acid and one or more of C 1 to C 6 alkyl (meth)acrylates SOand in which at least 50 percent of the acid groups in 0 o a the copolymer have been neutralized with alkali (see o our EP-A-0245987) Such high molecular weight ao0 copolyraers are, however, unsuitable for compatibilizing Q 0 O 0 o o low foam nonionic surfactant with polycarboxylated polymer in an acidic rinse aid formulation as phase oo separation is found to occur.

c We have now unexpectedly found that low foam 0 on nonionic surfactant can be compatibilized with polycarboxylated polymer, and a stable acidic rinse aid can be formed, by using, as compatibilizer or stabilizer, further ronionic surfactant.

According to the present invention there is provided a stable composition suitable for use as, or in, an acidic rinse aid, which comprises:low foam nonionic surfactant; (ii)polymer (hereinafter for convenionce referred to as "polymer") having a weight average molecular weight of 1,000 to 250,000 and being a homopolymer of acrylic acid, methacrylic acid, maleic acid, 2-acrylamido-2-methylpropane sulfonic acid or acrylamide, or being a copolymer comprising units derived from two or more of acrylic acid, methacrylic; acid, ethacrylic acid, rnaleic acid, itaconic acid, hydroxyacrylic acid, C 1 toC4 OQ00 lkyl (mot.) acrylates or amides, for example 0000,ethyl acrylate, 2-acrylamido 2- 00 00methylpropane sulfonic acid (AMPS) styrene, 00 0 0acrylamide, isobutadiene, dimethylaminoethyl 0o1 ~t-BAM) Vo (iii) further nonionic surfactant (nonionic 0 1 cosurfactant) having a cloud point of 70 0 C or above, e.g. 80*C or above; and OP U (iv) water.

0 00 The present invention also provides a method of 0C' stabilizing an aqueous composition comprising a mixture of low foam nonionic surfactant (which by its requirement of being low foaming will have a cloud point of less than 70 0 C) and~ polymer having a weight average molecular weight of 1,000 to 250,000 and being a homopolyrrer of acrylic acid, methacrylic acid, maleic acid 2-acrylamido-2-rnethylpropane sulfonic acid or acrylamide, or being a copolymer formed from two or more of acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, hydroxyacrylic acid, Cl to C 4 al~kyl (meth)acrylates or amidesp e.g. ethttl acrylate, 2 acrylamido 2 methylpropane sulfonic acid (AM~PS,' rstyrene, acrylamnide, isobutediene, dime thylaminoethyl methacrylate (DMAEMA) and t-butyl acrylamile (t-BAM) the method comprising incorporating 4n said composition nonionic cosurfactant having a cloud point of 701C or above, e.g. 800C or above.

In this specification, unless specifically stated otherwise, all quantities expressed as parts by weight for the low foam nonionic surfactant, polymer and further nonionic surfactant are per 100 parts by weight of low foam nonionic surfactant, 0000 polymer, further nonionic surfactant plus water.

0 T'he low foam nonionic surfactant may, for 0 Q Qexample, comprise any known low foam nonionic 0 surfactant useful in machine dishwashing or rinse aid ~O 0 0 applications. Suitable low foam nonionic surfactants 0 o 0 include: 0C to C2 fatty alcohol /ethylene oxide codnsts poyxprpln 6 po22ytyn o ~condensates;al polyoxypropylene polyoxyethy e 0 C 0condensates; alkyl polyoxyethylene -polyoxypropylene 0 U 0 0 cccondensates; polyoxyalkylene glycols; benzyl ethers of L% polyoxyethylene condensates of alkyl phenols; and 0butylene oxide capped alcohol condensates, e.g. having the fcormula:a 0011 )y0 0 4 e~O o 0 wher 0C is aC H to where R s t alkyl group, y has an average value of 3,5 to 10, and x has an average valve of to 1.5. Typical commercially available low foam nonjionic surfaictants include: Triton CF-10 (an alkylaryl polyetbt'e) and Triton DF-16 (a modified polyoxyalkylated alcohol) manufactured by Rohm and Haas Company; Pluronic L-62 (a polyoxyethylone polyoxypropylene block copolymer) Lutensol 1 4 F 403 and tutensol Lr 404 manufactured by BASF; and Antarox 8 .BL-330 (a modified linear aliphatic alcohol polyethoxylated and ciloro-terminated compound) manufactured by GAF Corporation.

The composition of the invention may, for example, comprise at least 1 part by weight, preferably at least 5 parts by weight, and more preferably at least 10 parts by weight, of the low foam nonionic surfactant. Up to 60 parts by weight, preferably up to parts by weight, and more preferably up to 40 parts by weight, of the low foam nonionic surfactant may, for oo' 0 example, be present in the composition.

0000 0 In one embodiment of the invention, the o o polymer is a homopolymer of acrylic acid, methacrylic o o acid or maleic acid, or is a copolymer formed from two 00 0 OO 0 C oo or more of acrylic acid, methacrylic acid, ethacrylic OO 0 o °ag acid, maleic acid, itaconic acid, hydroxyacrylic acid,

C

2 to C 4 alkyl (meth)acrylates or amides and 2-acrylamido 2 methylpropane sulfonic acid.

0 o t The polymer, used in the composition of the 00 C invention, may be a polycarboxylated polymer.

Dplm The weight average molecular weight of the 0 o a polymer is at least 1,000 and is preferably up to 100,000, more preferably up to 70,000. The o0 polymer may be used in the free acid form, or in the O 0 0 l .oo partially neutralised or neutralised, e.g, alkali metal or ammonium salt, form when producing the compsition of the invention, but is preferably used in the partially neutralised form as it may then be unnecessary to carry out a pH adjustment step to achieve the desired acidic pH.

Suitable commercially available polymers include Acrysol LMW 45 (an acrylic acid homopolymer which is neutralised and has a weight average molec'l.ar weight of 4500), and Acrysol LMW (an acrylic acid homopolymer which is fully neutralised and has a weight average molecular weight of 4500).

9 The composition of the invention may, for example, comprise at least 0.5 parts by weight, preferably at least I part by weigjht, of thu polymer. Up to 20 parts by weight, preferably up to parts by weight, and more preferably up to 5 parts by weight, of the polymer may be present in the composition.

Suitable nonionic cosurfactants include alkyl aryl poly-ther alcohols having an average of at least ten ethylene oxide units per molecule; and alkyl 0o #0 polyether alcohols having an average of at leant ten 000 ethylene oxide units per molecule. Preferably, the 0 0 ,0 Vo cosurfactant is a reaction product of ethylene oxid 0o with an octyl or nonyl phenol such as a compound of the 0o 0 0o0 foriu a: 0 0 C.) 0

O

0 Ii y-(OCH2CI2 O 11) l o 0 in which x has an average value of at least suitable commercially available materials having o 0 0 the formula include: Triton X 165 (average value ooo of x 16); Triton X 305 (average value of x Triton X 405 (average value of x 40); and Triton X 705 70; (average value of x 70); and suitable commercially available matorials having the formula (If) include: Triton N 150 (average value of x z Triton N 302 (average value of x 30); Triton N 401 (average value of 40); Triton N 998 (average value of x 100); and Triton N 998 100% (average value ot x 100); all of these materials being manufactured by Rohm and Haas Company, The composition of the invention imay' for example, comprise at least 0.2 parts by weight, preferably at least 0.5 parts by weight, of the n~onionic cosurfactant. Up to 10 parts by wieight, preferably up to 5 parts by weight, of the nonionic cosurfactant may, for example. be present in the c-,omposition.

it is to be understood that the co.-,position of the nvetio ma copris e one or more of each of the low foam nonionic surfactant, polymer and nonionatc oosurfactant. In one embcdiment of the invention, tile total amount of low foam nonionic surfactant, polymer, nonionic cosurfactai-t and weater is I00% by weight of the composition. ivninmycmrs The composition of theivnonmycprs other additives, for example, ont or more of ,4equestrants such as nitrilo triacetic acid (NTA), ethylene cliamine tetraacetic acid (EDTA) phosphonates, citric acid, or sodium citrate, and water-miscible C solvents such o! isopropano. or propylene glycol.

4xamples of suitable phosphonatee include U Q0 1 -hydro: :y-e thy lont-,-bi s-pho sphonic acid, nitrilo-tris (methyleno phosphonic acid), nQ otlylenediamino tetra (mothylene phosphonic acid) diethylene triamirie penta (mathylene phosphonic acid) Q Q ~and, hexamethylene, ciaMine tetra (methylene phosphonic acid) .suitable commercially available phosphonates include Dequest-2006t -202.6, -2046s -2056, and -2066, manufactured by Monlsanto, and1 My~on -PO60, -P2201 -P200 4 -P3101 and -P400, manufactured by Warwick international, For, example, based on the total weight of the compositiong tDPT\ may be present in an amount of up to 2% by weight, NTA may be present in an amrount of up to 4% by weiqht, citric acid, may be present in an amount of up to 10t by weight, or phosphonates may be present xn an amount of tip 'to 2t by weight,. if mnore than one su~ch sequesterlr additive is present, then, the amounts, of such additives present will require appropriate adjustmvent. The ,ibove-mentioned acidic materials, useful as optional additives, can be used in the acid, partially neutralized or fully neutralized form.

Table I below gi1ves examples of a number of formulations accordinq to the present invention, the figures quoted for each component being percentages by weight based on~ the total weight of the foramlation iA the balance bninUj water.

Q 0 00 0 0 0 Table 1 F~ormulation Low foam nonionic s urfa ctant (Triton DFI 6) Nonionic cosurfactant (Triton X-3 05) Polyiner (Acrysol LMW45 or Citc:ic EL-'TA acid Dequest Decjuest 2006 2016 Dequest, 2046 Deguest Dequest 2056 20G6 13 We have found that it is possible to make compositions according to the present invention which remain stable for several weeks at 400C, for at least days at room temperature, and pass five freeze/thaw cycles. Whilst not wishing to be bound by theory, it is thought that this stability is due to the formation of a microemulsion by the addition of the nonionic cosurfactant. Two observations support the formation of a microemulsion. Firstly, in the absence of the nonionic cosurfactant, the composition is turbid and quickly separates into two or more phases, but upon addition of the nonionic cosurfactant the composition 4

O

becomes transparent. This transparency is believed to be due to the formation of a microemulsion in which the particle sizes are too small to result in scattering of the light. Secondly, upon addition of the nonionic cosurfactant, a stable dispersion is s[ontaneously formed, that is, is formed without input of mechanical energy, e.g. without agitation. In oil/surfactant/water systems, in which a homogenous phase is not formed, it is known that the addition of a cosurfactant can produce spontaneous formation of a stable dispersion due to the formation of a microomulsion, and it is SJo believed that a similar situation is occurring in the case of the compositions of the present invention.

When used as, or in, a rinse aid, e.g. a rinse aid for automatic dishwashers, the composition of the invention may promote the wetting of a substrate, and may reduce spotting of the substrate when subsequently dried. These properties of the composition may also make it suitable for other uses, for example, as, or in, glass window) cleaning or retal cleaning compositions.

i4 The present invention will now be further illustrated by way of the following examples in conjunction with the accompanying drawing, the examples being for illustrative purposes only and not to be construed as imposing any limitation on the scope of the invention:- Example 1 This example illustrates the need to utilise a nonionic cosurfactant to stabilise an aqueous composition comprising low foam nonionic surfactant and polymer. A number of formulations were prepared on comprising low foam nonionic surfactant, 0 0 S, polymer, water, and, in some formulations, nonionic cosurfactant. The stability of these formulations S0o against phase separation at 40 0 C for 24 hours (or 0 0 0 o 1 longer) was measured and the results obtained are given 0 11o .oO in Table 2 below.

0000 o ao 0o o0 00 o S0ooo 0 010000 0 0 15 000 0 0000 0 00 0 0 0) 0 00 00 0 0 0 0 0 o 00 00000 0 00 0 0 Formulation Coriponet Low f oam nonionic surfactantM polymer nonionic cosurfactant Wa ter S table Table 2 2 2 3 4 5 6 7 8 Parts By Weight 10 10 30 30 50 50 20 5 5 2 2 2 2 10 0 1 f) 3 0 4 0 4 84 Yes 68 65 No Yes 48 44 No Yes 66 Yes Triton DF-16 (a modified polyalkoxylated alcohol) **eqg Acrysol LMW45 (acrylic acid neutralised wt aver mol, wt. 4500) Se.g, Triton X-305 (octyipheno lethoxy late with an average 30 ethylene oxide units per molecule) The total weight of each of the formuilations was 100 parts by weight.

.1

I

16 From Table 2 it can readily be observed that the formulations in accordance with the present invention formulations 2, 4, 6 and 8) were stable, whereas the comparative formulations formulations 1, 3, and which did not contain nonionic cosurfactant, were not stable.

As previously stated, the presence of po.ymers, e.g. polycarboxylated polymers, in acidic rinse aids is o aadvantageous as such polymers inhibit the precipitation o0 of hardness ion salts from the water in which the rinse o oo aid is used. However, prior art rinse aids have the °o disadvantage that none, or very little, polymer can be Q 0 4 o o o used otherwise phase separation of the low foam 0 °o nonionic surfactant and polymer is found to occur in the rinse aid.

So 0The presence of the cosurfactant, used in the 0 present invention, enables greater concentrations of 0 00 S0o0 polymer to be present in the rinse aid, resulting in C0 increased efficiency in inhibition of precipitation of 0° hardness ion salts from water in which the rinse aid is used, without rep'Iting in phase separation of the 0 o, polymer and the low foam nonionic surfactant. That is, the cosurfactant enables stable compositions comprising 0 0 low foam nonionic surfactant and polymer to be produced in which higher concentrations of polymer can be present than could be used in the prior art compositions.

The ability of the nonionic cosurfactants in enabling the production of stable aqueous compositions comprising low foam nonionic surfactant and polymer, e.g. polycarboxylated polymer, was investigated by comparing the light transmittance of formulations 4 and 8 of Table 2 formulations according to the present invention) with a prior art formulation 17 containing no nonionic cosurfactant, the prior art formulation being an aqueous composition of 30 percent by weight low foam nonionic surfactant, 10 percent by weight isopropanol and 60 percent by weight water.

Light transmittance can be used as an indication as to whether or not precipitation of hardness ion salts is occurring in the formulations since any such precipitation will reduce the light transmittance.

The light transmittance of each of the three "formulations, when added to soft water, medium hard water and hard water, was determined. The results are 'o shown in the accompanying drawing which is in the form t 0 of a graph in which axis x is the degree of hardness of 0 the water with A representing soft water, B 0a 0 o °oo representing medium hard water and C representing hard water, axis y is the percentage light transmittance, SOo is the line obtained for formulation 8 of Table 2, oo (ii) is the line obtained for formulation 4 of Table 2, 0a 0 and (iii) is the line obtained for the prior art o00o formulation.

e 0 o opo aFrom the graph it can clearly be seen that the formulations according to the present invention o oo (represented by lines and (ii) have a 0 0 0oo0 substantially higher light transmittance, i.e. greater o oooO So inhibition of hardness ion salt precipitation, than the prior art formulation (represented by line (iii) in medium and hard water.

The greater inhibition of hardness ion salt precipitation exhibited by the compositions of the present invention over the prior art composition is attributable to the ability to form, in accordance with the present invention, stable compositions having a higher concentration of polymer than can be used in the prior art composition.

38 Lines and (ii) of the accompanying graph also demonstrate that, the higher the concentration of polymer in the rinse aid, the greater the inhibition of hardness ion salt precipitation, particularly in medium hard and hard waterand hence the higher the light transmittance,; line representing the formulation comprising 10 parts by weight of polymer and line (ii) representing the formulation comprising 2 parts by weight of polymer.

Example 2 This example illustrates two procedures for the preparation of the compositions of the present t invention.

Procedure A:- 0 00 0 g To the water was added the polymer, then the low °0 0 foam nonionic surfactant was added, and finally the nonionic cosurfactant was added.

3 0 0 Q 0 Procedure B:- 0 00 q 0 0 o o To the water was added the low foam nonionic 0" 0o surfactant, then the polymer was added, and finally the cosurfactant was added.

A number of formulations according to the invention were prepared using the above procedures and the stability of the formulations at 40 0 C for 24 hours (or longer) was determined. The results are given in Table 3.

Table 3 Formulation 9 10 11 12 13 24 a 0 a 0 0 0 0 00 0 to 0 0 00 0 000 00 0 0 0 00 Procedure 14 B Component Parts by Weight polyacrylate homopolyrner 3.0 0 0 3.0 0 0 wt aver mol wt 4,500 acrylic acid! maleic acid 0 3.0 0 0 3.0 0 Copolymer, wt aver mol wt 10,000 acrylic acid/ ethacrylic 0 0 3.0 0 0 acid copolymer, wt aver mol wt 3,500 low foam nonionic* surfactant 20 20 20 20 20 nonionic 2 2 2 2 2 2 cosurfactant** Water 75 75 75 75 75 Stable Yes Yes Yes Yes Yes Yes 20 Triton DF-16 Triton X 305 The total weight of each of the formulations was 100 parts by weight. From Table 3 it can be observed that, in the case of Triton DF-16 as low foam nonionic surfactant, either procedure A or procedure B can be used to prepare stable compositions in accordance with the present invention. Table 3 also indicates that stable compositions are still produced when the polycarboxylated polymer is varied.

In some cases, however, for example when alkoxypolyethoxy polypropoxy benzyl ether is used as the low foam nonionic surfactant, the order of addition of the components of the composition is important.

Table 4 below illustrates the stability of compositions according to the present invention prepared using the above procedures A and B and two further procedures C 0o and D, procedure C being the addition of po00 polymer to the water, followed by the addition of o 0 0 0o nonionic cosurfactant and finally addition of low foam nonionic surfactant, and procedure D being the addition 0 of nonionic cosurfactant to water, followed by the 0 0baddition of low foam nonionic surfactant and finally o polymer. In each of these compositions, the low foam nonionic surfactant was an alkoxypolyethoxy polypropoxy benzyl ether.

Table 4 Formulation 15 16 17 18 Procedure A B C D Stability unstable unstable stable stable k This example illustrates that the procedure(s) by which formulations according to the present invention may be prepared may vary depending on the chemical structure of the low,, foam nonionic surfactant.

The terms "Triton" and "Acrysol" are trademarks of Rohm and Haas Company.

00 Ij 0

Claims

1. A stable composition suitable for use as, or in, an acidic rinse aid, which comprises:- low foam nonionic surfactant; (ii) polymer having a weight average molecular weight of 1,000 to 250,000 and being a honicpolymoer of acrylic acid, rnethacrylic acid, inaleic acid, 2 -acrylamido-2-me thy 1propane sulfonic acid or acrylamiide, or being a copolymer comprising units derived from two or more of ,crylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, hydrol-yacrylic acid, C 2 I to C 4 alk~yl (meth) acrylates or amides, 2-acrylamido 2 methyipropane sull'onic acid, styrene, acrylamile, isobutadiene, dime thy laniinoe thyl1 methacrylatet and t-butyiacrylamide; (iii) further nonionic surfactant having a cloud point of 70"C or above r1Y-.8QQ abovra; an d (iv) water.

2. A composition as claimed in claim 12, in which the polymer is a homopolymer of acrylic acid, methacrylic acid or maleic acid, or a copolymer formed from two or more of acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, hydroxyacrylic acid, C02 to C 4 alk~yl (meth)acrylates or amnides and 2-acrylamido 2 methyipropane su3.fonic acid. -23-

3. A composition as claimed in claim 1 or claim 2, in which the polymer is a polycarboxylated polymer.

4. A composition as claimed in any preceding claim, in which the low foam nonionic surfactant comprises one or more of C 6 to fatty alcohol/ethylene oxide condensates; polyoxypropylene-polyoxyethylene condensates; alkyl polyoxypropylene-polyoxyethylene condensates; alkyl polyoxyethylene-polyoxypropylene condensates; polyoxyalkylene glycols; benzyl ethers of polyo,,yethylene condensates of alkyl phenols; and ,I butylene oxide capped alcohol condensates. A composition as claimed in claim 4, in which the butylene oxide capped alcohol condensates have the S formula: 0 no R (0C 2 H 4 y (OC 4 Hg) x OH S" where R is a C 8 to C 1 8 alkyl group, y has an average value of 3.5 to 10, and x has an average value of 0.5 to 0 0 6. A composition as claimed in any preceding claim wherein the further nonionic surfactant has a cloud point of 800C or higher. 0

7. A compositLon as claimed in anry preceding claim, in which the low foam nonionic surfactant is present in an amount at least 1 part by weight per 100 parts by weight of plus (iv).

8. A composition as claimed in claim 7 in which the low foam noioionio surfactant is present in an amount of at least 5 parts by weight per 100 parts by weight of (iii), plus (iv). 906 ~1 M6,mttl 071,41,231 r res -24-

9. A composition as claimed in claim 8 in which the low foam nonionic surfactant is present in an amount of at least 10 parts by weight per 100 parts by weight of (iii), plus (iv). A composition as claimed in any preceding claim, in which the low foam nonionic surfactant is present in an amount of up to 60 parts by weight per 100 parts by weight of (iii) plus (iv).

11. A composition as claimed in claim 10, in which the low foam nonionic surfactant is present in an amount of up to 50 parts by weight per 100 parts by weight of (iii) plus (iv). l f

12. A composition as claimed in claim 11, in which the 4: "4 low foam nonionic surfactant is presen' in an amount of up to 40 parts by weight per 100 parts by weight of (iii) plus (iv).

13. A composition as cl&imed in any preceding claim, in o, b which the polymer (ii) has a weight average molecular weight of up to 100,000. 14, A composition as claimed in claim 13, in which the polymer (ii) has a weight average molecu ar weight of up to 70,000. A composition as claimed in any preceding claim, in which the polymer (ii) is partially neutralised.

16. A composition as claimed in any preceding claim, in which the polymer (ii) is present in an amount of at least 0.5 parts by weight per 100 parts by weight of (iii) plus (iv). 1 M,4hrtlim 14 t= 4 rOKre3,2 111__ 1 I

17. A composition :s claimed in claim 16, in which, he polymer (ii) is present in an amount of at least 1 part by weight per 100 parts by weight of (iii) plus (iv).

18. A composition as claimed in any preceding claim, in which the polymer (ii) is present in an amount of up to parts by weight per 100 parts by weight of (ii), (iii) plus (iv).

19. A composition as claimed in claim 18, in which the polymer (ii) is present in an amount of up to 10 parts by weight per 100 parts by weight of (iii) plus (iv). A composition as claimed in claim 19, in i ich the polymer (ii) is present in an amount of up to 5 parts by weight per 100 parts by weight of (iii) plus (iv).

21. A composition as claimed in any preceding claim, in which the further nonionic surfactant (iii) comprises alkyl aryl polyether alcohols having an average of at 2 least ten ethylene oxide units per molecule; and alkyl polyether alcohols having an average of at least ten ethylene oxide units per molecule. 22, A composition as claimed in claim 21, in which the alkyl aryl polyether alcohols comprise compounds of the formula;- C 8 7 (OCH 2 CH 2 )OH (I) or C 9 H9 (OCH 2 CH 2 )OH (II) y i~y 9OI27.1mndatO7la.A72224rohlcs,25 r i -26- in which x has an average value of at least

23. A composition as claimed in any preceding claim, in which the further nonionic surfactant (iii) is present in an amount of at least 0.1 parts by weight per 100 parts by weight of (iii) plus (iv).

24. A composition as claimed in claim 23, in which the further nonionic surfactant (iii) is present in an amount of at least 0.5 parts by weight per 100 parts by weight of (iii) plus (iv). A composition as claimed in any preceding claim, in which the further nonionic surfactant (iii) is present in an amount of up to 10 parts by weight per 100 parts by weight of (iii) plus (iv). S*26. A composition as claimed in claim 25, in which the further nonionic surfactant (iii) is present in an amlount of up to 5 parts by weight per 100 parts by weight of (iii) plus (iv). S 0 o 0 27. A method of stabilizing an aqueous composition comprising a mixture of low foam nonionic surfactant and polymer having a weight average molecular weight of 1,000 to 250,000 and being a homopolymer of acrylic acid, o methacrylic acid, maleic acid, 2-acrylamido-2- methylpropane sulfonic acid or acrylamide, or being a copolymer comprising units derived from two or more of acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, hydroxyacrylic acid, C i to C4 alkyl (meth)acrylates or amides, 2-acrylamido-2-methylpropane sulfonic acid, styrene, acrylamide, isobutadiene, dimethylaminoethyl methacrylate, and t-butylacrylamide, the method comprising incorporating in said composition further nonionic surfactant having a cloud point of 901 07,irtAdUL071&i:22314 rokres, -27 or aT-ve.

28. A method as claimed in claim 27, comprising incorporating in said composition further nonionic surfactant having a cloud point of 80°C or above.

29. A method as claimed in claim 27 or 28, in which the low foam nonionic surfactant, polymer, and further nonionic surfactant, and amounts thereof, are respectively as defined in any one of claims 2 to A composition as claimed in claim 1, or a method as claimed in claim 27, substantially as hereinbefore described with reference to the Examples. DATED this 6th day of December 1990. ROHM AND HAAS COMPANY By Its Patent Attorneys DAVIES COLLISON 0, #4 901207litnzdat.071,aA\22314roLrs,27