US3764559A

US3764559A - Detergent compositions

Info

Publication number: US3764559A
Application number: US00112856A
Authority: US
Inventors: W Mizuno; T Brunelle; L Rue; S Crecelius
Original assignee: Economics Laboratory Inc
Current assignee: Ecolab Inc
Priority date: 1968-12-10
Filing date: 1971-02-05
Publication date: 1973-10-09
Anticipated expiration: 1990-10-09
Also published as: SE366340B; GB1292120A; DE1961959A1; FR2025760A1

Abstract

Detergent compositions containing maleic anhydride polymers.

Description

United States Patent [1 1 Mizuno et al.

[ 51 Oct. 9, 1973 DETERGENT COMPOSITIONS [75] Inventors: William G. Mizuno; Thomas E.

Brunelle, both of St. Paul; Larry M. Rue, Grove Heights; Samuel B. Crecelius, St. Paul, all of Minn.

[73] Assignee: Economics Laboratory, Inc., St.

Paul, Minn.

[22] Filed: Feb. 5, 1971 [2]] Appl. No.: 112,856

Related US. Application Data [63] Continuation-in-part of Ser. No. 782,569, Dec. 10,

1968, abandoned.

[52] US. Cl 252/99, 252/89, 252/135, 252/161, 252/187 [51] Int. Cl ..C11d 7/54 [58] Field of Search 252/99, 187, 161, 252/89, 135

[56] References Cited UNITED STATES PATENTS 2/1966 Tuvell o 252/132 5/1971 Sabatelli 252/99 X Primary ExaminerMayer Weinblatt V Attorney-Pendleton, Neuman, Williams & Anderson [5 7] ABSTRACT Detergent compositions containing maleic anhydride polymers.

3 Claims, 2 Drawing Figures PATENTEU 9*975 3.764.559

FIG. I.

PPM AVAILABLE CHLOR/NE TIME IN MINUTES FIG.2

&

PPM AVAILABLE CI-ILOR/NE 102'004'5 6'0 120 [30 2&0

TIME IN MIIVU TES INVEIV TORS WILLIAM G. M/ZUNO THOMAS EBRUNELLE SAMUEL B.C1QECELIUS LARRY M. QUE wy/ x110 #Mw AT TY'S DETERGENT COMPOSITIONS This application is a continuation-in-part of our copending application Ser. No. 782,569 filed Dec. 10, 1968, now abandoned.

This invention relates to low foaming detergent compositions for use in automatic dishwashers.

For use in automatic dishwashing machines of the type used in homes and in commercial facilities it is desirable that the detergent exhibit low foaming properties since the washing action of such equipment is dependent upon the scrubbing effect of a vigorous jet or spray of liquid which would be rendered relatively ineffective if cushioned by the action of large amounts of V foam. In this respectdetergents for use in automatic dishwashers differ from laundry detergents. Laundry detergents usually contain substantial amounts of anionic surface active agents to increase sudsing (foaming) since the fabrics to be washed are immersed in the detergent solution with soil removal being dependent upon emulsification, peptization and mechanical action by tumbling or by means of an agitator. In both detergents salts of phosphoric acids are generally employed to achieve a chelating or sequestering action on magnesium or calcium ions present in the wash water. The wide-spread use of phosphate sequestering agents in detergents has contributed significantly to the contamination of rivers and lakes into which the sewage effluent is emptied. Phosphate contamination of rivers and lakes results in increasing the growth of algae as well as over-fertilization of the waters (eutrophication). There is serious concern over the pollution problem and reduction of phosphate contamination is highly desirable.

The use of nitriloacetate salts as replacements for phosphate salts as chelating agents in wash detergent compositions has been considered. Nitriloacetate salts such as trisodium nitrilotriacetate monohydrate and disodium monohydrogen nitrilotriacetate monohydrate appear to be satisfactory for use in laundry detergents and in non-chlorinated dishwashing detergents. However, nitriloacetate salts cause rapid degradation of the chlorine releasing agents frequently employed in detergents thus reducing the amount of available chlorine. Furthermore, nitriloacetate salts would be suspected of contributing to nitrogen pollution of rivers and lakes.

It is a principal object of this invention to provide novel detergents for use in automatic dishwashers, which detergents contain a non-phosphate chelating agent for the magnesium and calcium ions which may be present in the wash water.

It is a further object of this invention to provide novel detergents for use in automatic dishwashers which detergents contain a non-phosphate chelating agent for magnesium and calcium ions which chelating agent is relatively non-detrimental with respect to chlorinecontaining components of the detergent.

Dishwashing detergents normally employ a large proportion of inorganic alkaline detergent salts (builders) such as carbonates, bicarbonates, silicates, borates, perborates and phosphates. Such inorganic salts as sodium chloride and sodium sulfate are also frequently employed as fillers to increase the bulk of the composition. The phosphate salts, in addition to providing alkalinity for detergency, serve as water softening agents by chelating or sequestering magnesium and calcium ions present in hard wash water.

It has now been found that the amount of phosphate salts in dishwashing detergents can be reduced or eliminated while still achieving desired chelation of magnesium and calcium ions. This is accomplished in accordance with this invention by the use in dishwashing detergents, as chelating agents, low molecular weight linear polymers of maleic anhydride with vinylacetate. Structurally these polymeric materials can be represented as follows:

wherein M is hydrogen, ammonium or an alkali metal and n is an integer such that the product has a relative viscosity of from 1.0 to 10.0 when determined on a 4 percent aqueous solution at 25 C.

For the purpose ofthis invention, it is desired that the relative viscosity of the said maleic anhydride polymers be relatively low. Since there are certain inherent viscosity differences depending upon the particular polymer product, the preferred relative viscosities will vary; the limiting criteria being that the polymers be susceptible to handling and blending with the other components of the new detergent as well as affording satisfactory performance. For example, with a Vinylacetatemaleic anhydride polymer it is preferred that the relative viscosity range be from 1.0 to 10.0 when determined on a 4 percent aqueous solution at 25 C. (acid form).

Copolymerization of maleic anhydride with unsaturated organic materials is known in the art. Thus, for example, U.S. Pat. No. 2,938,016 relates to the production of low molecular weight olefin-maleic anhydride polymers having the above characteristics.

Vinylacetate-maleic anhydride copolymers are prepared by charging 98.10 grams (1.0 mole) maleic anhydride, 86.06 grams (1.0 mole) vinylacetate, 2.42 grams (0.01 mole benzoyl peroxide and 1,000 milliliters of an organic solvent, such as benzene, toluene, xylene or mixtures thereof, into a suitable reaction vessel. The reaction vessel, if not sealed, should be equipped with a reflux condenser, an agitator, a means of heating and a thermometer or other means of determining temperature.

The mixture is heated to C. at which time the copolymer begins to form and depending on the solvent system may require cooling. The temperature is maintained at 80-85 C. for l to 5 hours, preferably 2 to 2-V2 hours. The product can be isolated as the anhydride at this stage by filtering the insoluble copolymer. If the acid form of the copolymer is desired, grams of water can be added and the mixture stirred and heated for an additional 30 minutes. The acid form of the copolymer will then precipitate and can be recovered from the solvent. If, for example, the sodium salt form is desired, the addition of sodium hydroxide can be made at the time water is added. The copolymer thus obtained has a relative viscosity at 1.0 to 10.0 (depending on solvent used for the reaction). The viscosity is determined on a 4 percent aqueous solution.

The dishwashing detergent compositions of this invention comprise a major proportion of an alkaline detergent salt or salts together with a described linear copolymer of maleic anhydride-vinylacetate. While phosphate salts are generally considered to be alkaline detergent salts, such phosphate salts can be employed in the compositions of this invention in reduced amounts H LI lZ wherein Z is the oxyalkylatable material, A is the radical derived from the alkylene oxide which can be, for example, ethylene, propylene, butylene oxide, etc., n is z a be i l g t g ermine}? m whlgh a 5 a number determined by the moles of alkylene oxide 15 6 6 use a g 051) 15 reacted, for example 10 to 2000 or more and z is a me a sue as car d s ik "ii" g whole number determined by the number of reactive "P perborates an t l epreSemam/F a 9' oxyalkylatable groups. Where only one group is oxlme detergent Falls are P ylakylatable as in the case of substituted or unsubsticarbonate, sodium metasilicate, sodium borate, sodium 10 tuted monofunctional phenol, a Straight or branched peworate and monosofhum orthophosphafes chain alcohol, then 1 =1. Where Z is water or glycol z sodiumsesquicarbonate, potassium carbonate, s o dium where Z is glycerol 2 =3, etc" hydfoxlde hydroxlde sofhum sequlslhcate f. A nonionic as in e above where 2 =1 and chain is sodium orthosilicate, potassium b1carbonate, potasterminated with alkyl or benzyl ether, slum silicates, alkaline condensed phosphate salts such A nonionic such as in d but terminated with benzyl as tetrasodium pyrophosphate or tetrapotasslum pyroether group and phosphate and poll/phosphates Such as sodlum mpoly' h. A nonionic similar to c but containing organic phosphate chlorine groups.

The mclu slon f know? to the The chlorine-releasing agent provides available chloslfch as sod'um mmte f alummates Zmcates] rine during the washing operation and serves to destain d um mer a tobengothiazol e, etc does not constltt t dishware and reduce film formation on glassware. Repa departure from this invention. Likew se, the inclusion resemative chlorine releasing agents are in general, of fillers known to the art, such as sodium chloride, soalkali metal polychloro isocyanurates, Sulfate and the l not commute a depar' chloroisocyanuric acid, dichloroisocyanuric acid, soture from the mventlon, dium or potassium dichloroisocyanurate, [(mono tri- Preferred COl'flPOSlIlOI'lS of the nvention also include chloro) tetra (monopotassium dichloronpem a deffammg foammg 9 Surfactant and a taisocyanurate, dichlorodimethyl hydantoin, succincblormefrffleasmg agent' The P 1 t chlorimide, chloramine-T, chloromelamine, chlori- Y' addmonal detergencylwhfle,mamilammg f nated trisodium phosphate and solid chlorinated causmg at a low leve Desired c i f or tic soda such as described in U.S. Pat. No. 3,166,512. the nonionic surfactants are that they exhibit a cloud The composition ofthe dishwashing detergents of the of less than about 45 1 percent concentra' present invention can be summarized as follows: tion in water and a surface tension not lower than about Broad Range Preferred Range dynes/centimeter at 0.1 percent concentration 1n 35 by weight by weight water at 25 C. The surfactants should be low-foaming Non-phosphate Alkaline in nature. As determined by the known Ross-Miles omefgemsahs 95 25 60 f l f f t t h. h Alkaline Phosphate Salt 0 to 10 to 30 03m 351,? 0w Oammg sur ac an ls one w P Maleic Anhydride Copolymer 5 to 65 20 to 50 vides an initial foam of not more than about millimegglnioniculrfactam O0 to 8 8.5 m 2.0 orine e easing Agent to 10 .5 to 4.0 ters m height and not more than 15 millimeters foam 40 Neutralsahs Such as Nacl height after 5 minutes. Representative low foaming Na,so 0 to 40 0 to 20 nonionic surfactants are: The detergent compositions of this invention can be a. Alkyl phenoxy polyethenoxy ethanol, compounded as dry powders by mixing the various b. Alkyl phenoxy polyethenoxy benzyl ether, components in dry form. The maleic anhydride copolyc. Polyethenoxy polypropenoxy polyethenoxy etha- 45 mers can be added in the anhydride, acid or salt forms,

nol block or random polymers, although for optimum activity the salt form is ultid. Polyalkylene glycol which is prepared by condensmately desired and preferred. Alternatively, aqueous ing propylene oxide with water or propylene glycol solutions of one or more of the various components can to form polypropylene glycol and then condensing be prepared and the solutions introduced separately propylene oxide with the oxyethylated polypropylinto the dishwasher in desired proportions.

ene glycol so as to have an alternating hydro- Representative dishwashing compositions of the phobehydrophile structure; and present invention are illustrated in Table 1 below, the

e. Oxyalkylated compounds of the general formula amounts shown being on a weight percentage basis.

" ABLE 1 Components 1 11 111 IV V V1 V11 V111 IX X X1 X11 X111 XIV Maleic anhydride 19.8 38.0 40.0 35.0 20.0 19.0 15.0 50.0 25.0 25.0 15.0 30.0 15.0 15.0

copolymer Caustic soda 20.0 21.0 21.0 25.0 20.0 25.0 20.0 20.0 Soda ash 29.3 30.1 20.0 18.0 23.0 31.8 18.5 21.5 26.5 Sodium silicate 29.5 29.5 27.0 30.0 20.0 29.0 25.0 25.8 25.8 24.0 23.0 20.0 20.0 27.0 Sodium polyl9 0 15.0 19.0 36.8 25.0 21.0 20.0 15.0 15.0

phosphate Sodium borate 10.0 Sodium chloride 15.0 Sodium sulfate 20.0 20,0 Chlorine-releas- 1.2 1.2 2.0 1.2 3.2 3 2 3.2 3.0 2.0 2 0 2.0 3.0

ing agent Nonionic 1.2 1.2 1.0 2.0 2.0 2.0 1.5 1.5 1.5 Total: 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

The following examples illustrate the preparation of the detergent compositions of this invention.

EXAMPLE 1 Formulation I of Table I was prepared by blending in a food mixer 12 parts of a liquid nonionic surfactant and 19.0 parts of sodium tripolyphosphate followed by the addition of 29.3 parts soda ash. After several min utes of blending, 29.5 parts of sodium metasilicate were added followed by 1.2 parts of sodium dichloroisocyanurate. After the addition of sodium dichloroisocyanurate the blend was mixed for one minute and stored. Subsequently 24.0 grams of the above blend were charged to a dishwashing machine followed by the addition of a concentrated aqueous solution of the soclium salt of a copolymer of vinylacetate-maleic anhydride. The acid form of this copolymer had a relative viscosity of5.07 when determined on a 4 percent aqueous solution at 25 C. This sodium salt polymer solution was employed in an amount to provide 6. 0 grams (anhydrous basis) of the sodium salt polymer and thus the finished product corresponded to Formulation I of Table I.

EXAMPLE 2 1.2 parts of a liquid nonionic defoamer were blended with 30.1 parts of soda ash. After several minutes mixing the blend was free-flowing and uniform and then 29.5 parts of sodium metasilicate were added followed by 1.2 parts of sodium dichloroisocyanurate. The blend was mixed for 1 minute and stored. Subsequently 18.6 grams of the above blend were charged into a dishwater followed by the addition of a concentrated aqueous solution of a sodium vinylacetate maleic copolymer. The acid form of this copolymer had a relative viscosity of 5.07 when determined on a 4 percent aqueous solution at 25 C. This polymer solution was employed in an amount to provide 1 1.4 grams (anhydrous basis) of the polymer and thus the finished product corresponded to Formulation II of Table I.

EXAMPLE 3 A formulation corresponding to Formulation VIII of Table I was prepared by blending 25.8 parts of sodium metasilicate and 21.0 parts caustic soda. After the mixture appeared uniform, 3.2 parts of sodium dichloroisocyanurate were added and mixed for an additional 1 minute. Subsequently grams of the above blend were charged into a dishwasher followed by the addition of a concentrated solution of sodium vinylacetate maleate copolymer. This polymer solution was employed in an amount to provide 15 grams of the solid polymer (anhydrous basis) and thus the finished detergent corresponded to Formulation VIII of Table 1.

EXAMPLE 4 25.8 parts of sodium metasilicate and 21.0 parts of caustic soda and 25.0 parts of sodium tripolyphosphate were blended together for several minutes until the mixture was uniform. Then 3.2 parts of sodium dichloroisocyanurate were added and the mixture blended for an additional 1 minute. Subsequently, 22.5 grams of the above blend were charged into a dishwasher followed by the addition of a concentrated solution of a sodium vinylacetate maleate copolymer. The acid form of this copolymer had a relative viscosity of 1.42 when determined on a 4 percent aqueous solution at 25 C. This polymer solution was employed in an amount to provide 7.5 grams of the solid and thus the detergent correspond to Formulation IX of Table 1.

EXAMPLE 5 Formulation I of Table I was prepared by blending in a food mixer 1.2 parts of a liquid nonionic surfactant and 19. 0 parts of sodium tripolyphosphate followed by the addition of 29.3 parts soda ash. After several minutes of blending 29.5 parts of sodium metasilicate and 19.8 parts ofa sodium vinyl-acetate maleate copolymer were added. The acid form of this copolymer had a relative viscosity of 1.42 when determined on a 4 percent aqueous solution at 25 C. When the blend appeared uniform, 1.2 parts of sodium dichloroisocyanurate were added and the blend was mixed for 1 minute and stored. For the evaluation in an automatic dishwashing machine 30 grams of the above blend were charged into the machine. The finished product correspond to Formulation I of Table 1.

EXAMPLE 6 Formulation VIII of Table I was prepared by blending in a food mixer 50 parts of sodium vinylacetate maleate copolymer, 21 parts of caustic soda, and 25.8 parts of sodium metasilicate. After several minutes of blending 3.2 parts of sodium dichloroisocyanurate were added and the blend was mixed for one minute and transferred to a glass jar for storage. The acid form of the copolymer had a relative viscosity of 1.42 when determined on a 4 percent aqueous solution at 25 C. For evaluation in an automatic dishwashing machine 30 grams of the above blend were charged into the machine. The finished product corresponded to Formulation VIII of Table I.

The performance of chelating agents in dishwashing detergents is best evaluated by testing the detergents under dishwashing conditions. This test consisted of racking a home type dishwashing machine with dummy" dishes and glasses plus four clean test glasses racked in appropriate positions. Forty grams of soil (2 lbs. olemargarine creamed with 227 grams of non-fat dried milk solids) are spread equally and uniformly on four 10-inch dinner plates. The dishwashing machine is filled with hot water (l40 F.), charged with 30 grams of test detergent and operated in the wash portion of the cycle for 5 minutes; the machine is emptied and refilled for a 3-minute rinse, followed by another 3-minute rinse. The dishes are allowed to air-dry. This completes a dishwashing cycle. After completion of five such cycles, the glasses are evaluated for filming and spotting. The transparent nature of the glasses makes them more amenable to grading than opaque dishware and furthermore a filmed glass is more conspicuous than a filmed dish.

Using the above procedure, various detergent form ulations were tested with the following results.

TABLE n.- PERFORMANCE OF DETEIICIENT Foki/IuLATIoNs WITH PAT-{T or ALL OF S ODIUM TRIPOLYPHOSPHATE (STPP) REPLACED WITH VINYLACETATE MALEIC SALT (VA/MA) Percent chelate in formulation (System: percent org. chcl/perccnt S'lll) Filming and spotting ratings on glass Product of Example VA/MA/STPP= 19.8/l9

except only STPP employed City water llilltl wallcr" Excellent Good Excellent Good Excellent Good Excellent Good Excellent Good Excellent Good Performance rating: Excellent-no visible filming or spotting, Good very slight filming and/or spotting.

Fairmoderate filming and/or spotting.

2 City Water ofapproximately 68-70 p.p.m. hardness as CaCO3.

Hard Water-city water hardened to give approximately 400 p.p.m. hardness as CaCo,,.

The above results show that part or all of the sodium tripolyphosphate can, with good results, be replaced in detergent formulations by the chelating polymers disclosed herein.

As indicated, chelating agents employed in dishwashing detergents should not adversely affect chlorinereleasing agents employed therein so as to significantly reduce the amount of available chlorine. A comparison of detergents containing various chelating agents is graphically illustrated in FIGS. 1 and 2.

The data plotted in FIG. 1 was determined on detergent formulations dissolved in water at 140 F. at a pH of 11.7. The detergent concentration was 0.5 percent by weight/volume of the test solution. The data plotted in FIG. 2 was determined on formulations dissolved in water at 140 F. at a pH of 12.1. The detergent concentration was 0.5 percent by weight/volume of the test solution.

Curve A is a plot of the chlorine available at various times with respect to a detergent formulation similar to Formulation I (Table I) except that all of the maleic anhydride polymer 19.8 parts) was replaced with sodium tripolyphosphate.

Curve C is a plot of the chlorine available at various times with respect to a detergent formulation similar to Formulation I (Table I) wherein the chelating polymer is sodium vinylacetate maleate having a relative viscosity of 6.9 when measured in a 4 percent aqueous solution in the acid form.

Curve D is a plot of the chlorine available at various times with respect to a detergent formulation similar to Formulation I (Table I) except that the chelating agent employed is trisodium nitriloacetate monohydrate.

Curve E is a plot of the chlorine available at various times with respect to a detergent formulation similar to Formulation IX (Table I) except that parts of the maleic anhydride copolymer was replaced with sodium tripolyphosphate.

Curve G is a plot of the chlorine available at various times with respect to a detergent formulation-similar to Formulation IX (Table I) wherein the chelating polymer is sodium vinylacetate maleate having a relative viscosity of 6.9 (4 percent aqueous solution of the acid form of the copolymer).

Curve H is a plot of the chlorine available at various times with respect to a detergent formulation similar to Formulation IX (Table I) wherein the maleic anhydride copolymer was replaced by an equal weight of trisodium nitriloacetate monohydrate.

By referring to these graphs it will be seen that the polymeric chelating agents employed in accordance with this invention provide significantly greater chlorine stability than do nitriloacetate salts.

The low molecular weight linear polymers of maleic anhydride with vinylacetate are employed in dishwashing detergent compositions in accordance with this invention to serve as chelating or sequestering agents for magnesium and calcium ions present in hard water. By serving this important function, it is possible to eliminatc or significantly reduce the amount of phosphate salts normally employed for this purpose.

The chelating ability of the polymers employed herein is shown by a comparison with various agents known to possess chelating properties for magnesium and calcium ions. A method for determining the relative chelation values of various chelating agents consists of weighing a known amount of the chelating agent (0.25 to 1 gram), dissolving the agent in about milliliters of distilled water in a 250 milliliter beaker, adding 10 milliliters of 2 percent sodium carbonate, adjusting the pH of the solution to the desired level (if the sample is an anhydride, it is first heated to l00 C. in water until hydrolyzed, converted to the salt with sodium hydroxide the pH is adjusted before and after the addition of sodium carbonate to the desired pH), and making up to milliliters volume and titrating with 0.25 M calcium acetate (44.1 grams/liter calcium acetate monohydrate) until a faint but permanent turbidity is obtained indicating excess calcium ions leading to the formation of insoluble calcium carbonate. The milligrams of CaCO chelated per gram of agent is given by the equation: milligrams CaCO chelated/gram 25 X milliliters of Ca Acetate Solution/weight of sample The titrations may be carried out at room temperature or at elevated temperatures.

A summary of the evaluation of known chelating agents is shown in Table III.

TABLE III Comparison of Chelation Values of Various Chelates at pH 11 Except where Noted Otherwise (2325 C) mgs CaCO chelated Chelating Agent Evaluated per gram of sample Meso tartaric acid I20 a precipitate formed within about minutes after the titration was completed.

2 vinylacetate-maleic anhydride copolymer prepared via benzoyl peroxide in benzene solvent.

The chelating ability of the maleic anhydride polymers employed in accordance with the invention is apparent from the above.

Another desirable property of the maleic anhydride derivatives employed in accordance with this invention is their ability to prevent precipitation of ferric hydroxide in aqueous solution. Ferric hydroxide is known to form an insoluble precipitate when a ferric salt such as ferric chloride is made alkaline. Many municipal and home supply waters contain varying degrees of iron. Many municipal waters contain on the order of 0.3 parts per million iron, and as high as 1.0 parts per million iron. Many well waters contain as high as several parts per million iron.

The iron exists in natural water as ferrous salt and is quickly oxidized by air or oxidizing agents such as hypochlorite to ferric form which then forms insoluble ferric hydroxide when the water is made alkaline such as in an alkaline detergent solution. The iron may discolor clothes or stain dishes. In the latter case where the dishes are rewashed frequently, such as in eating establishments, iron stain may occur when the iron level is as low as 0.2 parts per million. Presently such stained dishes must be processed by immersion in strong, mineral acids muriatic acid being frequently used. Thus, the use of an iron sequestering agent in a washing compound is of substantial benefit in such waters containing even a relatively small amount of iron to minimize the need for processing of dishware for iron stain removal. Unexpectedly the maleic anhydride derivatives employed in accordance with this invention have been found to possess an unusual ability to prevent ferric hydroxide precipitation.

This property was assessed by taking various increments of a stock solution of a chelating agent, adding water to bring up the solution to 89 milliliters volume, adding 1 milliliter of a ferric chloride solution (to give final concentration of 41 parts per million Fe then adding milliliters of 2 percent sodium carbonate solution with agitation. Observation of these solutions was made after 16 hours and after 2 weeks storage at room temperature. Solutions either had reddish brown precipitate which settled to the bottom, or had a very faint turbidity or were completely clear amber colored by visual inspection. The end point reported was the minimum concentration of chelate to give completely clear amber solution. We presume this phenomenon to be chelation though we do not wish to be bound to any mechanism or theory regarding the tie-up of the ferric ion.

A summary of the chelating value of these maleic anhydride derivatives and several of the well-known chelates is given in Table IV. As will be noted in this table, the sodium vinylacetate maleate copolymers had chelation values several orders of magnitude greater than the so-called iron chelates which are items of commerce and sold specifically as iron chelates (sodium and alkanolamine salts of alkyl diamino-polyacetic acids, N,N-di(2-hydroxyethyl) glycine. Also included in this evaluation are EDTA'Na NTA'Na '2H O and STPP. The latter three products are used in detergent formulations for calcium and magnesium chelation and are not regarded as iron chelates.

Sodium and alkanolamine salts of'alkyldiaminopolyacetic acids 200 500 N,N-di(2-hydroxyethyl)glycinc 200 500 Sodium ethylene diamine tetraacetate 200 500 Sodium nitrilotriacetate 540 540 Sodium tripolyphosphate 540 540 Ten milliliters of sodium carbonate solution to give a final concentration of 2000 parts per million was added to milliliters of a solution containing 4] parts per million FeCl; (final concentration) and varying increments of the chelating agent. Final pH was 10.8 when measured with Corning Model l2 glass electrode pH meter.

2 Solutions were observed after overnight and after 2 weeks standing at room temperature (20-25 C.).

The detergent compositions of this invention are admirably adapted for use in automatic dishwashing equipment of all types. In addition, these detergents can be advantageously utilized in laboratory glassware washers, for in-place cleaning of dairy plant equipment and the like and in spray cleaning operations where non-foaming or defoaming detergents are required. The use of the maleic anhydride copolymers in dishwashing detergents affords numerous advantages including l) the ability to sequester hardness ions in water thereby softening the water and improving dishwashing efficiency, 2) reduction in phosphate or nitrogen pollution of lakes and rivers, 3) do not dissipate available chlorine when used in chlorine-containing detergents.

Those modifications and equivalents which fall within the spirit of the invention are to be considered a part thereof.

What is claimed is:

l. A machine dishwashing composition consisting essentially of from about 10 to percent by weight of a non-phosphate alkaline detergent salt, from 0 to 40 percent by weight of an alkaline detergent phosphate salt, from 0 to 8 percent by weight ofa nonionic surfactant which in the Ross-Miles foam test provides an initial foam of not more than about 45 milliliters in height and not more than about 15 milliliter foam height after five minutes, from 0 to 10 percent by weight of a chlorine-releasing agent, from 0 to 40 percent by weight of a neutral inorganic salt, and an amount sufficient for chelation of magnesium and calcium ions ranging from 5 to 65 percent by weight of a copolymer in the acid or salt form of maleic anhydride and vinylacetate in a 1:1 molar ratio, said copolymer having a relative viscosity of from about 1 to 10 when determined at 25 C. on a four weight percent aqueous solution thereof.

2. A machine dishwashing composition consisting essentially of from about 10 to 95 percent by weight of a non-phosphate alkaline detergent salt, from O to 40 percent by weight of an alkaline detergent phosphate salt, from 0 to 8 percent by weight ofa nonionic surfactant which in the Ross-Miles foam test provides an initial foam of not more than about 45 milliliters in height and not more than about 15 milliliter foam height after 5 minutes, from O to 10 percent by weight ofa chlorinereleasing agent, from to 40 percent by weight of a neutral inorganic salt, and an amount sufficient for chelation of magnesium and calcium ions ranging from to 65 percent by weight of an alkali metal salt of a copolymer of maleic anhydride with vinylacetate in a 1:1 ratio, said copolymer having a relative viscosity of from about 1 to when determined at C. on a four weight percent aqueous solution thereof.

3. A machine dishwashing composition consisting essentially of from about 25 to 60 percent by weight of a non-phosphate alkaline detergent salt, from 10 to percent by weight of an alkaline detergent phosphate a copolymer in the acid or salt form of maleic anhydride and vinylacetate in a 1:1 molar ratio, said copolymer having a relative viscosity of from about I to 10 when determined at 25 C. on a four weight percent aqueous solution thereof.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CURRECTION PatentNo. 3,764,559 Dated October 9, 1973 lnv fl William G. Mizuno, Thomas E. Brunelle,

Larry M. Rue and Samuel B. Crecelius It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 11, line 10, before "ratio" insert molar Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD M.PLET HER,JR. C a MARSHALL DANN Attestlng Off-166T v 1 Commissionerof Patents FORM po'wso (169) USCOMM-DC 60376-P69 i [1.5. GOVIRNMEKT PRINTING OFFICE: 969 0-356-JSI UNTTED STATES PATENT 'GFFICE CERTHECATE 0F CORREQTION Patent No. 3364 559 Dated October 9, 1973 lnv n fl William G. Mizunon Thomas E. Brune11e Larry M. Rue and Samuel B. Crecelius It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

(SEAL) Attest:

EDWARD M.FLETC IHER,JR. C o MARSHALL DANN Attestlng Off cer Commissioner of Patents USCOMM-DC 60376-P09 a v.5. GOVERNMENT ranmm: orncr: I959 o-au-Ju F ORM PO-105O (10-69)

Claims

2. A machine dishwashing composition consisting essentially of from about 10 to 95 percent by weight of a non-phosphate alkaline detergent salt, from 0 to 40 percent by weight of an alkaline detergent phosphate salt, from 0 to 8 percent by weight of a nonionic surfactant which in The Ross-Miles foam test provides an initial foam of not more than about 45 milliliters in height and not more than about 15 milliliter foam height after 5 minutes, from 0 to 10 percent by weight of a chlorine-releasing agent, from 0 to 40 percent by weight of a neutral inorganic salt, and an amount sufficient for chelation of magnesium and calcium ions ranging from 5 to 65 percent by weight of an alkali metal salt of a copolymer of maleic anhydride with vinylacetate in a 1:1 ratio, said copolymer having a relative viscosity of from about 1 to 10 when determined at 25* C. on a four weight percent aqueous solution thereof.
3. A machine dishwashing composition consisting essentially of from about 25 to 60 percent by weight of a non-phosphate alkaline detergent salt, from 10 to 30 percent by weight of an alkaline detergent phosphate salt, from 0.5 to 2.0 percent by weight of a nonionic surfactant which in the Ross-Miles foam test provides an initial foam of not more than about 45 milliliters in height and not more than about 15 milliliter foam height after 5 minutes, from 0.5 to 4.0 percent by weight of a chlorine-releasing agent, from 0 to 20 percent by weight of a neutral inorganic salt, and an amount sufficient for chelation of magnesium and calcium ions ranging from 20 to 50 percent by weight of a copolymer in the acid or salt form of maleic anhydride and vinylacetate in a 1:1 molar ratio, said copolymer having a relative viscosity of from about 1 to 10 when determined at 25* C. on a four weight percent aqueous solution thereof.