US2618604A - Polyphosphate-containing detergent compositions having decreased corrosivity toward aluminum - Google Patents

Description

Patented Nov. 18, 1952 John R. Schaefier, Reading, Ohio, assignor to The Procter and Gamble Company, Ivorydale, Ohio, a corporation of Ohio No Drawing. Application November 25, 1949, Serial No. 129,527

9 Claims.

The present invention relates to a method of protecting aluminum surfaces against corrosion by detergent solutions. More especially it relates to detergent compositions containing calcium-sequestering polyphosphates and an agent for protecting aluminum.

For many years it has been known that the the surface brightness of aluminum objects is destroyed by washing them in detergent solutions which are alkaline in character. The most common of such detergent solutions are those of soap, which at room temperature have a. pH of about 9.5 to 10.5, although when built with alkaline salts such for example as sodium carbonate or trisodium orthophosphate the pH often rises to 11 or higher. Such surface reaction, which usually increases with increasing pH and increasing temperature, appears to be a function of the hydroxyl ion content of the solution, and means of protecting aluminum against hydroxyl ions are known, sodium silicate, for example, being widely used for this purpose.

Within recent years calcium-sequestering phosphates have come into widespread use, both alone as water softeners and cleaning agents and also in combination with synthetic organic detergents, particularly those which contain a proportion of sodium sulfate or other essentially neutral inorganic salts of an alkali metal. Neither these phosphates nor their mixtures with synthetic organic detergents are highly alkaline in nature, but nevertheless their aqueous solutions, both with and without sodium sulfate, act upon aluminum. Under mild conditions (i. e. of time of exposure, of temperature and of concentration) the action appears to be a surface discalcium-sequestering phosphates and agents which inhibit the corrosion of aluminum. It is another object to provide detergent compositions which are safe for use with aluminum and which comprise mixtures of synthetic organic detergents, calcium-sequestering phosphates and corrosion inhibitors.

I have found that I can realize these and other objects of the invention by using water-soluble berylliumsalts in suitable small amounts in mixture with calcium-sequestering phosphates or mixtures thereof with synthetic organic de tergents of either the anionic or the non-ionic type.

When I use the term calcium-sequestering phosphates I mean those phosphates which have the power to protect calcium ions (as well as certain other polyvalent metal ions such for example as magnesium) against precipitation in aquego ous solutions, this protection resulting, it is believed, from removal of free calcium ions from the solution to form soluble complex calcium-containing phosphate ions. The phosphates which possess this power are water-soluble salts of phosphoric'acids which are poorer in water of concoloration, but under more drastic conditions, v

' cipitate in aqueous solutions.

It is an object of my invention to provide means whereby aluminum can be protected against the tarnishing and corroding action of solutions of calcium-sequestering phosphates. It is another object to provide compositions comprising both stitution than orthophosphoric acid, such for example as tetrasodium pyrophosphate, pentasodium triphosphate (sometimes referred to as tripolyphosphate), hexasodium tetraphosphate and hexasodium hexametaphosphate, as well as the various corresponding acid salts such for example as disodium dihydrogen pyrophosphate, and also soluble salts of basic ions other than sodium, such for example as pentapotassium triphosphate. All such calcium-sequestering phosphates have a plurality of phosphorus atoms in their molecular structure, and all will hereinafter be referred to generically as polyphosphates. In the above discussion, hexasodium tetraphosphate and "hexasodium hexametaphosphate are placed in quotation marks to indicate that the salts so designated may in fact be mixtures rather than simple chemical individuals. The tetraphosphate to which I refer is that compound or mixture which is described in U. S. Patent 2,031,827, and the hexametaphosphate to which I refer is the glassy variety, sometimes called Grahams salt, which is described in U. S. Patent 1,956,515.

The synthetic organic detergents which are present in many of the detergent compositions of my invention are amphiphilic in nature, by which I means that they have both hydrophilic and lipophilic properties, resulting from a molecular structure characterized by a strongly by.-

drophilic portion and a strongly lipophilic portion. While other hydrophilic groups have been used in synthetic organic detergents, the particular hydrophilic groups to which I refer herein are (a) for anionic detergents, the sulfuric acid ester group or the sulfonic acid group or their water-soluble salts, or (b) for non-ionic detergents, one or more hydroxyl groups, supplemented by ether oxygen atoms and by an ester, amide, ether or thioether linkage to the lipophilic portion of the molecule. The lipophilic (or hydrophobic) group is commonly a hydrocarbon radical containing 10 or more carbon atoms, and may be either an open chain, a closed chain or a combination of the two.

The specific anionic synthetic organic detergents which I contemplate in my invention include water-soluble salts of organic sulfonic acids and sulfuric acid esters, such as alkyl sulfates and sulfonates, alkylated aryl sulfonates. sulfated and sulfonated esters, sulfonated amides and the like. The more important non-ionic synthetic organic detergents are the polyalkylene oxide derivatives which can be represented by the general formula RXY(Z) in where R is a monovalent hydrocarbon radical of about 10 to 30 carbon atoms, such for example as C12Hzsor X is an ester. ether, thioether, or amide linkage, such for example as 2 is the monovalent residue remaining after removing one hydroxyl group from a polyalkylene glycol of at least 10 carbon atoms, there being 2 to 3 carbon atoms in each alkylene unit thereof, such for example as (CH:CH:)10H 01' -(CH:CHO);H

- HI and w is an integer, from '1 to 5.

The term soap-compatible" is useful to distinguish the anionic and non-ionic types of synthetic organic detergents,which may be used in conjunction with soap without precipitating or decomposing it or destroying its detergent/properties, from the cationic type. members of which latter type destroy soap and are not compatible with it.

The usefulness of beryllium salts as protectors of aluminum in solutions of polyphosphates or mixtures thereof with soap-compatible organic synthetic detergents will be perceived from the descriptions which follow. For ease of'presentation, there will be given results of tests inmost of which the same general procedure was followed, although it will be understood that other procedures are equally suitable in demonstrating the utility of my invention. Except when othermained constant at 30.7 cm".

wise noted, strips of sheet aluminum, known in industry as 33" aluminum, having a surface area of 30.7 cm. were used. This is an aluminum alloy containing 1.2% manganese. These strips were first polished to remove tarnish or other surface impurities, then rinsed with distilled water, dried, weighed, immersed in 300 cc. of the test solution for 3 hours at F., removed, rinsed, dried, reweighed, and examined visually. The appearance often gives a qualitative estimate of the effect of the test solution, while the loss in weight gives a quantitative figure.

For further ease in presentation and in order that attention may be focused upon the inventive element, namely, the corrosion inhibitor, only a limited number of variations in detergent composition and in test conditions will be shown. -It will therefore be understood that the following descriptions are illustrative only and that the invention is not limited thereby but only by the terms of the appended claims. Unless otherwise indicated, 0.5% solutions of Detergent A were used, having the approximate formula shown in Table 1.

TABLE 1 Detergent A 40% Sodium lorol 1 sulfate 40% Sodium sulfate 20% Pentasodium triphosphate Lorol herein designates the alkyl radical of mixed fatty alcohols derived from coconut oil.

To these solutions, inhibitors were added extra, e. g. when 4% Beck" was used, it is meant thereby that an amount of BeCh equal to 4% of the weight of Detergent A was added to the solution, thus bringing the total concentration therein to 0.52%.

Salts of beryllium with strong acids are acidic in reaction and tend to lower the pH of the detergent solutions. while in most cases the polyphosphates are alkaline. Unless otherwise indicated, the solutions were commonly adjusted to a predetermined pH value of 7.5 (measured at room temperature) by adding a neutralizing agent before immersing the aluminum strips.

Table 2 shows the inhibiting action of beryl-- lium nitrate in varying amount. It will be noted that 2, 4 and 6% Be(NO:)z are equivalent respectively to 0.38, 0.75 and 1.13% BeO, as shown in the second column of the table. The third column shows the per cent BeO based upon the weight of polyphosphate present. The tests were run in 200 cc. of solution.

TABLE 2 Inhibitor added L0 in weight season, I BeO i BeO (1118-) Percent Percent 0 0 5. 4 38 l. 88 2. 2 75 3. 75 l. 1 l. 13 5. 63 3 1 Percentages based on weight of total composition. 1 Based on weight of polyphosphata.

In making comparisons of corrosion inhibiting power, it has been found to be important to keep a constant ratio of volume of solution to area of aluminum. This is illustrated in Table 3.

where the volumes were varied but areas re- In all succeeding work herein recorded the volume was 300 cc.

TABLE 3 Low in weight (1.08.)

Volume of solution t 4 m percen perce Be(NOa): Be(NO;)|

The data of Table 4 show that the protective action of beryllium salts is not restricted to a particular type (38) of aluminum; it is generically true of aluminum surfaces such as are normally encountered in industry and in the home. The tests were run on an aluminum foil commercially produced for kitchen use. Spectegraphic analysis of this foil indicated:

1 to 100% aluminum 0.1 to iron 0.01 to 1% copper, gallium, manganese, silicon and vanadium 0.001 to 0.1% chromium, manganese, nickel,

titanium and zinc 0.01% or less of silver, arsenic, calcium, molybdenum, sodium, lead and tin The tests were with Detergent A as usual, using beryllium nitrate.

TABLE 4 Loss in Be(NO:): weight,

That beryllium salts other than the nitrate are also effective is shown in Table 5. Here it be seen that the efiectiveness is roughly proportional to the BeO equivalent of the salt used.

' The tests were with Detergent A as usual, using 4 of each salt.

l Percentage based on weight of total composition. I

9 Based on weight of polyphosphate present.

I Gaininweight.

Data of Tables 2 to 5 illustrate the fact that solutions of detergents, such for example as Detergent A, containing 2% or more of a calciumsequestering phosphate, tend to corrode aluminum even at pH values as lowas 6 to 8, and that such corrosion can be decreased or eliminated by adding to the solution any water-soluble beryllium salt in sufficient amount, at least 0.5% BeO based upon the polyphosphate content of the solution being commonly required, in order to have any marked effect. Furthermore, they illustrate the fact that, under normal conditions of.

usage, corrosion of aluminum is to a large extent either avoided or markedly decreased when detergent compositions such as these contain beryllium salts equivalent to BeO equal in weight to at least 0.5% of the weight of the polyphosphate present.

As the pH of the detergent solution increases, the amount of corrosion occurring under otherwise similar conditions normally increases and the need for an inhibitor increases. While the beryllium salts are still effective at pH values as high as 9 or 10, their effectiveness is not so great as at lower pH values. Their utility is much diminished at pH values above 10. While I do not wish to be bound by theoretical considerations, I believe this to be due to the fact that there are at least two types of corrosion of aluminum, one type being caused to a large extent by the action of hydroxyl ions and therefore increasing with the pH of the solution, and the other type being due to the action of polyphosphate ions and therefore increasing with the polyphosphate content of the solution. The former type of corrosion is more commonly encountered and can be alleviated by known corrosion inhibitors such for example as sodium silicate. The latter type is less common, and against this type I have unexpectedly found the beryllium salts to be effective. Thus in the presence of polyphosphates, corrosion occurs even when the solution is neutral, and this action is: prevented by beryllium salts, while silicates are:

of little'value in this case. As the pH of such; solutions increases, the magnitude of the corrosion increases, the effectiveness of silicates increases, and the effectiveness of beryllium salts relative thereto decreases.

That the corrosion by such detergent solutions at pH values below about 9.5 or 10 is due to the polyphosphate ion rather than to the hydroxyl ion, and furthermore that it is not a function in general of ions containing phosphorus but is restricted to the polyphosphates as illustrated by the following observations. Corrosion tests were run in the usual manner with Detergent A and with Detergent B, in which the triphosphate of Detergent A was replaced with trisodium orthophosphate. Solutions of these two detergents were adjusted to pH 7.5 and to pH 9.5 and aluminum strips were then inserted, with the following results:

Since the above solutions, at each pH level, contained the same concentration of hydroxyl ions, the relative inertness oi orthophosphate and the activity of triphosphate is obvious. Furthermore, while corrosion in the presence of triphosphate is nearly twice as great at pH 9.5 as at pH 7.5, this increased corrosion cannot be attributed to hydroxyl ions alone, but also and principally to triphosphate ions.

Table 7- presents data illustratin the fact that beryllium salts are effective inhibitors of corrosion caused by polyphosphate-containing detergents, even at pH values as high as 9.5 o'r 10. Solutions of Detergent A, with or without added beryllium salts, were adjusted to pH 7.5, and duplicates'were adjusted to pH 9.5. Corrosion tests gave the following results:

1 Percentages based on total composition. 1 Based upon the weight of polyphospbate.

The data of the preceding table illustrates the facts that while sodium orthophosphate does not produce appreciable corrosion of aluminum at pH values of 9.5 or lower, yet triphosphate does produce such corrosion, and the corrosion due to the triphosphate can be checked by beryllium salts. Table 8 presents data illustrating the facts that this corrosion effect is common to po yphosphates in general and is not restricted to triphosphate, and that beryllium salts act in the same manner with the other polyphosphates as with triphosphate. Three detergents were made according to the formula of Detergent A, except that in two of these, tetrasodium pyrophosphate or glassy hexasodium hexametaphosphate were substituted for pentasodium trlphosphate. Cor- Within limits, increasing amounts of beryllium salts afford increasing protection against solutions containing trlphosphate. Table 9 illustrates the fact that this is true also when the triphosphate is replaced by other polyphosphates, as in Detergent C which was similar to Detergent A except for substitution of glassy sodium hexametaphosphate for sodium triphosphate' therein. These tests were for 1 hour at 180 F.

TABLE 9 Inhibitor added Loss in weight, mg.

Detergent Detergent B80 A lPzOlt c (NaP a)a Percent Percent None 0 0 7. 3 3. 5 1.3% BeNOl)I .24 1.2] 4.5 2.3 2.6% Be N002... 49 2. 45 1. 8 .6 3.9% Be(N0;),.- 73 3. 65 1. 6 3

1 Percentages based on total composition. 1 Based on weight of polyphosphate.

In general, the effectiveness of beryllium salts is somewhat greater with detergents of low polyphosphate content (such as those used in the preceding tables) than in those of high polyphosphate content. This is illustrated in Table None 8 11, where various beryllium salts were used in conjunction with Detergent D, which had the formula shown in Table 10.

TABLE 10 Detergent D 18% Sodium lorol sulfate 14% Sodium sulfate 54% Pentasodium triphosphate 3.5% Unsulfated higher alcohols 2.5% Sodium carbonate 8.0% Water TABLE 11 Inhibitor added LOSS in weight, mg.

Salt 1 BeO 1 BeO 1 Percsnt Percent .227 BBC]: 02% 363(104):

1 Percentages based on total composition. I Based on weight of polyphosphate.

The effectiveness of beryllium salts with high polyphosphate detergents such as the above is greater at low DH than at high pH. This is 11- lustrated in Table 12, where Detergent D of Table 10 was used but where the pH of the solutions was adjusted to predetermined values before beginning the test.

1 Based on the weight of polyphosphate.

The effectiveness of beryllium salts is not limited to polyphosphate-containing detergent solutions in which the synthetic organic detergent is an alkyl sulfate. As previously stated, their effectiveness is eneric to polyphosphate-containing detergent solutions in which the synthetic organic detergent is of the soap-oompatible type. whether anionic or non-ionic. As long as pH is not too high, the inhibiting action of the beryllium salt is marked, irrespective of the particular soap-compatible synthetic organic detergent with which it is used. This is illustrated by the data of Table 14. Here four different types of commercially produced synthetics were used, namely, sulfated monoglyceride of coconut fatty acids in Detergent E, fatty acid ester of monoethanolamide of sulfoacetic acid in Detergent F, dodecyl thloether of polyethylene glycol in Detergent G, and sodium alkyl benzene sulfonate in Detergent H. The approximate analyses of these detergent compositions are shown in Table 13.

i MW

Deter- Deter- Deter- Detergent E gent F gent G gent H Percent Synthetic 27. 5 18 40 40 Percent N82S04 60. 47 40 40 Percent NazsPsoio 20 20 10 Percent N8P03)a Percent olyphosphate Solutions of these detergents, with and without beryllium salts, were used in the corrosion tests of Table 14.

TABLE 15 Materials present in solution Loss gg Sodium After After Na5P=0 n Lorol N 2280; Be(NOa)z 1 sulfate 1 hr. 5 hrs.

Percent Percent Percent 0. 1" 4 9 0. 1', t 02 0 4 0. 1" 2 6 0. 1?" 2 02 0 4 0. 1% 2 3 9 0. 1" 2 02 0 4 The beryllium salts of my invention can be added separately to the water in which the detergent is to be used, or they can be incorporated in the detergent either in the manufacture thereof or at any time thereafter. In the case of nonionic detergents, which are commonly manufactured and marketed in liquid form, the beryllium salts are conveniently dissolved in the liquid. In the case of anionic detergents, which are commonly encountered in solid form, usually as a powder, the beryllium salt can if desired be mechanically mixed with the detergent powder, although this procedure is often complicated by the deliquescent properties of many of the beryllium salts. In general I find that a simpler method is to add the beryllium salt to the aqueous paste of the detergent prior to the customary spray-drying or drum-drying of same. It will be understood that, aside from minor adjustment of pH which may become necessary, no serious com lications result iron; limited decomposition in: of the beryllium salt which may in some cases occur during heat drying. It appears to be the beryllium ion which is required for corrosion inhibition, and not the presence in the solution of any particular salt thereof.

Table 17 presents data illustrative of the oncetiveness of beryllium salts which are added to detergent compositions prior to heat drying thereof. Here aqueous pastes were first prepared by adding water to the mixtures of Table 16, the proportions being expressed as parts by weight.

TABLE 16 Detergent I Detergent I Sodium lorol sulfate 45 45 Sodium sulfate 45 45 Pentasodium triphosphate 10 10 Be(NOa)z 0 4 These pastes were drum dried in conventional manner and tests were made of the corrosive action on aluminumfoil, after having adjusted .the pH of the solutions to 7.5. Table 17 shows It is also frequently convenient in preparing detergent compositions to introduce the beryllium salt at a still earlier stage in the manufacture. Thus when sulfated or sulfonated syn-- thetics are used, basic beryllium carbonate can conveniently be dissolved in the caustic soda which is to be used in neutralizing the acid sulfuric reaction product. The effectiveness of basic beryllium carbonate is shown in Table 18 where a solution thereof in 30% caustic soda was added to Detergent D of Table 10, following which the 0.5% solutions were adjusted to pH values of 8.5 or 9.0 before beginning the test.

TABLE 18 Inhibitor added Loss in weight, mg.

Salt 1 B60 1 BeO pH 8.5 pH 9.0

Pcrcant Percent I Percentages based on total composition. 1 Based on weight of polyphosphate.

It will be understood that the invention is not restricted to any particular manner or mode of adding beryllium salts to the detergent solutions against which aluminum is to be protected, or of incorporating said salts in the detergent compositions. Any suitable method of so doing can be practiced.

Although in the preceding tables there have been recorded only figures showing the loss in weight of aluminum strips, visual appearance is also useful in establishing the protective action of beryllium salts. For example, aluminum kitchen saucepans were treated with 0.5% solutions of three detergent compositions for 16 hours at F. and were then examined visually for 11 tarnish and corrosion. The detergent compositions were as follows, expressed as parts by weight.

All solutions were adjusted to pH 7.5. None of the aluminum articles showed corrosion, i. e. reaction extending below the surface film, but Detergent L (containing triphosphate but no inhibitor) produced tarnishing, whereas neither Detergent K (containing no triphosphate) nor Detergent M (containing both triphosphate and. inhibitor) had any visible effect.

In order to accomplish satisfactory protection of aluminum, it is in general required that the beryllium salt, expressed as the equivalent weight of BeO, should be at least 0.5% of the weight of polyphosphate present, although the required amount varies somewhat with the kind of polyphosphate and other conditions. Larger amounts of beryllium salts are more effective, but effectiveness tends to level off as the proportion increases, so that only rarely is much benefit derived from increments ofBeO in excess of about 10% of the weight of polyphosphate. Furthermore, I prefer to use no more beryllium salt than the minimum which suffices for my purpose, because of harmful physiological effects sometimes caused by such salts.

An especially useful embodiment of the invention is to be found in detergent compositions comprising by weight from 10 to 98 parts of a soap-compatible synthetic organic detergent and from 2 to 60 parts of a polyphosphate, to which beryllium salts are added in amounts such as are described in the preceding paragraph, the polyphosphate content of such composition being less than 60% by weight. There may be present additionally substances which are without substantial effect upon aluminum and which do not interfere with the protection afforded by beryllium salts against the action of polyphosphates thereon. Water, sodium sulfate, sodium bicarbonate, sodium carboxymethylcellulose, starch, urea, etc. are examples of such other substances which may be found in detergent compositions of the type herein contemplated. Such substances, when present, are non-critical in nature. It will be understood that reference herein to a detergent, a phosphate, or a beryllium salt is intended to include mixtures of compounds of each of these classes, and that when the amount of the compound is stated, it is either the amount of a single compound or the total amount of a mixture of compounds of the same class. The use of such mixtures in any of the foregoing examples does not materially alter the results achieved, as herein set forth.

The effectiveness of beryllium salts being greatest within a limited pH range, as previously pointed out, I commonly adjust the pH of the solutions to between 6 and 10 when measured at room temperature, or in manufacturing the detergent I so adjust its alkalinity that its 12 solution will have a pH coming within this range. This adjustment of pH can be accomplished by adding an acid or an acid-reacting compound (such for example as an acid polyphosphate) if the pH is to be lowered, or an alkali or an alkaline-reacting compound (such for example as sodium hydroxide or sodium carbonate) if the pH is to be raised.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A detergent composition consisting essentially of a mixturefrom 10 to 98 parts by weight of synthetic organic detergent of the group consisting of anionic and non-ionic water-soluble synthetic organic detergents, from 2 to 60 parts by weight of a calcium-sequestering phosphate, a water-soluble beryllium salt, and a neutralizing agent in sufiicient amount to establish the pH of solutions of said composition between 6 and 10 when measured at room temperature, the amount of beryllium salt expressed as BeO being from 0.5% to about 10% by weight of said phosphate and sufiicient to lessen corrosion of aluminum by solutions of the composition.

2. A detergent composition-consisting essentially of a mixture of from 10 to 98 parts by weight'of a synthetic organic detergent of the group consisting of anionic and non-ionic watersoluble synthetic organic detergents, from 2 to 60 parts by weight of a calcium-sequestering phosphate, and an amount of a water-soluble beryllium salt equivalent in BeO content to from 0.5% to 10% by weight of said phosphate, said composition containing not more than 60% by weight of said phosphate and exerting in aqueous solu-- tions reduced corrosive action on aluminum.

3. A composition consisting essentially of a mixture of a calcium-sequestering phosphate and a water-soluble beryllium salt, the beryllium salt being present in an amount equivalent to from 0.5% to 10% BeO based upon the weight of said phosphate and sufficient to inhibit corrosion of aluminum by the calcium-sequestering phosphate component in aqueous solution of the composition.

4. The composition of claim 3 in which the beryllium salt is beryllium chloride.

5. The composition of claim 3 in which the beryllium salt is beryllium sulfate.

6. The composition of claim 3 in which the beryllium salt is beryllium nitrate.

7. The composition of claim 3 in which the calcium-sequestering phosphate is sodium pyrophosphate.

8. The composition of claim 3 in which the calcium-sequestering phosphate is sodium triphosphate.

9. The composition of claim 3 in which the calcium-sequestering phosphate is glassy sodium hexametaphosphate.

JOHN R. SCI-IAEF'FER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,037,566 Durgin Apr. 14, 1936 2,324,124 Williams July 13, 1943 2,419,805 Wegst Apr. 29, 1947

Claims (2)

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE FROM 10 TO 98 PARTS BY WEIGHT OF SYNTHETIC ORGANIC DETERGENT OF THE GROUP CONSISTING OF ANIONIC AND NON-IONIC WATER-SOLUBLE SYNTHETIC ORGANIC DETERGENTS, FROM 2 TO 60 PARTS BY WEIGHT OF A CALCIUM-SEQUESTERING PHOSPHATE, A WATER-SOLUBLE BERYLLIUM SALT, AND A NEUTRALIZING AGENT IN SUFFICIENT AMOUNT TO ESTABLISH THE PH OF SOLUTIONS OF SAID COMPOSITION BETWEEN 6 AND 10 WHEN MEASURED AT ROOM TEMPERATURE, THE AMOUNT OF BERYLLIUM SALT EXPRESSED AS BEO BEING FROM 0.5% TO ABOUT 10% BY WEIGHT OF SAID PHOSPHATE AND SUFFICIENT TO LESSEN CORROSION OF ALUMINUM BY SOLUTIONS OF THE COMPOSITION.

3. A COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF A CALIUM-SEQUESTERING PHOSPHATE AND A WATER-SOLUBLE BERYLLIUM SALT, THE BERYLLIUM SALT BEING PRESENT IN AN AMOUNT EQUIVALENT TO FROM 0.5% TO 10% BEO BASED UPON THE WEIGHT OF SAID PHOSPHATE AND SUFFICIENT TO INHIBIT CORROSION OF ALUMINUM BY THE CALCIUM-SEQUESTERING PHOSPHATE COMPONENT IN AQUEOUS SOLUTION OF THE COMPOSITION.