' Patented use. 24, 1 2,412,944 ' 1 UNITED ‘STATES 1 PATENT’ OFFICE 2,412,944 -mirnon or rnonucmo a DETERGENT __ _ ooMrosmoN , Frederick c. Bersworth, Verona, N. .1. No Drawing. Application June 9, 1944, Serial No. 539.595 ' ' 2 Claims. _ (01. 252-117) 2 This invention relates to detergent comp'osi- ; tions and more particularly to detergent compo sitions suitable for use in hard, saline, and hard saline water, and is an improvement invention of the invention described'and claimed in co 5 pending application Serial No. 539,595, ?led June 9, 1944, which application is assigned to the same solution is also miscible in all proportions with alkali metal-fatty acid soap compounds to form a plurality of detergent compositions that are also suitable for use in hard water'of various de grees of hardness, in water containing strong neutral electrolytes, and in hard-saline water, such as seasvater. As a speci?c embodiment of this invention, but assignee as the present invention. not as a limitation thereof, the invention will be One of the objects of the present invention is to provide a detergent composition for use in 10 described as it has been adapted to the forma; tion of a detergent composition consisting of an hard, saline, and hard-saline water.‘ equilibrium mixture of an acid-alkali metal salt Another object is to provide a composition hav of ethylene diamine tetracarboxylic acid and the ing detergent and deionization properties for use alkali metal salt of stearlcacid. In this example alone or in combination with alkali metal-fatty acid soap compounds in hard, saline and hard 15' an aqueous solution of the tetrasodium salt of saline water. _ ‘ - ethylene diamine tetracarboxylic acid contain ing one molar weight (or 380 grams) in 3% liters of water (3500 c; c.) having 9. PH of about 10.5 is agent‘ compatible with alkali metal-fatty acid digested under a re?ux condenser with 11/2 molar soap compounds in aqueous solutions. Other objects will be apparent as the invention 20 weights (427.5 grams) of stearic acid, at elevated Still another object is to provide a deionlzation ' ‘ is more fully hereinafter disclosed. ' In accordance with the disclosure of my co pending application Serial No. 539,595, above noted, I have discovered that the only alkali temperatures approximating the boiling point of the solution for an extended time interval until the pH of the solution approximates 8. The re sulting solution is ?ltered while hot, to remove metal salts utillzable as deionization agents and 25 therefrom any unsaponi?ed fatty acid, and then electrolyte-carrying agents with alkali metal fatty acid soap compounds in aqueous solutions are the acid-alkali metal salts of the aliphatic is cooled to atmospheric temperatures. At atmos~ pheric temperatures the solution solidi?es to a substantially transparent jelly which is 'com amino , polycarboxylic acids, particularly those pletely soluble in cold or warm water. To materially shorten the time interval of heat amino acids containing more than two carboxylic acid groups attached directly to amino nitrogens, such as the acid-alkali metal salts of ethylene diamine tetracarboxylic acid which in molar weight aqueous solution have a PH between 7 and 9.5, preferably those having a pH of approxi ms to obtain the saponi?cation ofthe stearic acid by the free alkali present in the aqueous solution of the tetra salt, the solution may be heated in an autoclave under a pressure of steam 35 approximating 20 pounds. ' The chemical reaction involved in this process is essentially one of saponi?cation of the stearic In accordance with the present invention 1 form acid by the caustic alkali set free in aqueous so a detergent composition consisting of an equilib lution by ionization of the tetrasodium salt of rium mixture of the acid-alkali metal salt of the amino acid, particularly ‘ethylene dianiine tetra 40 the amino acid. This salt in aqueous solution has a pH of about 10.5 and, in accordance with my carboxylic acid, and a mono-basic fatty soap acid, experiments, the tetra salt in aqueous solutions such as stearic acid, in aqueous solution having of about this concentration hydrolyzes with lib a pH within the range '7‘to 9.5 but preferably eration of two molecules of caustic alkali per approximating a pH of about 8, by saponifying the fatty acid in an aqueous solution of the tetra 45 molecule of tetra salt present. Stearic acid, in an amount somewhat in excess of that approxi alkali metal salt of the amino-acid until the pH mately suihcient to combine with one of the mole of the solution approximatesv 8 or is within the mately 8, . ‘ . -. cules of caustic alkali liberated by the tetra salt, This equilibrium solution of amino acid, fatty is preferably employed, to shorten the time in acid and caustic alkali, having a pH of about 8, 50 terval of heating required to obtain, by saponi? is a detergent composition suitable for use in hard cation of the stearic acid, a lowering of the pH water of various degrees of hardness, in water of the solution to the desired ?gure of pH 8 with containing neutral electrolytes such as sodium in the range 7 ‘to 9.5. chloride or sodium sulfate, and also in hard-saline The saponi?cation reaction proceeds to an equi water such as sea water. The said equilibrium 55 librium composition consisting essentially oi the range 7 to 9.5. 3 9,412,944 ~ acid-trisodium salt of the amino acid and the sodium salt of the fatty acid in aqueous solution at a pH of about 8. Lower and higher pH equi librium solutions may be obtained by appropri ate variations in the relative percentages of the tetra salt and fatty acid, and by variations in reaction time and reaction pressures, as one v skilled in the art may perceive. _~ 4 . water soluble alkali metal salts of the fatty acid, thereby lowering the pH of the solution to with in the range 7 to 9.5 and preferably to a pH of about 8. The precise amount of fatty acid re quired to obtain this desired result will vary with respect to variation in the amount of free alkali liberated by the amino acid salt in aqueous so lution, or present in the solution in addition Alternatively, I may form substantially the thereto. same detergent composition by digesting at ele 10 In place of a soap fatty acid, I may also em vated temperatures, one molar weight of the - ploy a large number of other organic acids, such amino acid and 11/2 molar weights of the stearic as the di-basic acids and poly-basic acids to neu acid in an aqueous caustic alkali solution of the tralize the free alkali of the solution and to ob same approximate volume containing about 4 tain Various equilibrium mixtures having a pH molar weights of caustic alkali (NaOH), until a within the range speci?ed which, while not nec solution having a pH of approximately 8 is ob essarily being detergent compositions, are mis tained. cible in all proportions with alkali metal-fatty The detergent composition obtained by the acid soap compounds to form a detergent compo~ practice of the above disclosed method is miscible sition containing the deionizing and electrolyte in all proportions with alkali metal-fatty acid carrying acid-alkali metal aliphatic polycarbox soap compounds to form detergent compositions ylic acid complex of the present‘invention and of suitable for use in a plurality of different types the invention of my co-pending application Be and kinds of hard waters, electrolyte-carrying rial No. 539,595, above identi?ed. / waters and in hard-saline waters. Having hereinabove described the present in As an illustration, in accordance with usual 25 vention generically and speci?cally and given one laundry practice a soap solution containing 10 speci?c example of the same, it is believed ap to 15% alkali metal-fatty acid soap compounds parent that the same may be widely varied with is usually employed to which soap solution vari out essential departure therefrom and all such ous water softening agents in proportion to the modi?cations and adaptations of the same are hardness of the water being used may be added 30 contemplated as may fall within the scope of the to form a stock soap solution. In accordance with the present invention, from 5 to 10% (dry weight) of the detergent composition of the above spe ci?c example, based on the weight of the soap compounds present in the soap solution, is added to the soap solution for use with medium to hard water; from 10 to 15% of the composition is added for use with hard to very hard water and following claims: What I claim is: 1. The method of forming an aqueous solution containing about one molar weight of the tri sodium salt of ethylene diamine tetracarboxylic acid and about 1 molar- weight of the sodium salt of stearic acid which comprises dissolving _ about one molar weight of the tetrasodium salt with water containing moderate amounts of elec of the said amino acid in a volume of water, add trolytes; and from 15 to 25% of the composition 40 ing thereto about 11/2 molar weights of stearic is added for extremely hard water or for water acid, and heating the solution for an extended containing relatively large amounts of electro time interval until the pH of the solution is sta ' lytes and for hard-saline water, such as sea wa bilized at a pH of about 8, and ?ltering the so ter. lution while hot to remove the excess stearic acid The addition of the detergent composition of present therein. the present invention to soap solutions or to solid ' 2. The method of producing a detergent com and liquid soap compounds presents no particu position consisting of a water soluble mixture of lar problem as the detergent is miscible in all an acid alkali metal salt of an aliphatic amino proportions with such soap compounds. In gen polycarboxylic acid having more than two car eral, identically the same practice as has here 50 boxylic acid groups attached directly to amino tofore been followed in the soap art is followed in nitrogens with at least one of the carboxylic groups the forming of bar, ?ake, powder, or liquid soap in excess of two unneutralized by alkali metal compositions including the detergent composi and an alkali metal salt of a monobasic fatty tion of the present invention or in the forming soap acid, which comprises forming an aqueous of concentrated aqueous soap solutions. , solution of the fully neutralized alkali metal salt In the adaptation of the present invention to of said amino acid, adding thereto the mono the forming of detergent compositions consisting basic fatty soap acid in such an amount required of a mixture of the acid-alkali metal salts of any to combine with at least one of the alkali metal of the other aliphatic amino polycarboxylic acids ions of each molecule of the salt of said amino heretofore recognized in the art as strong de 60 acid and to lower the pH of the solution to a ionizing agents and the alkali metal salt of a. soap pH within the range '7 and 9.5, heating the so fatty acid, substantially the same procedure is lution for an extended time interval to solubilize followed as hereinabove described, namely thev the mono-basic fatty soap acid as the alkali metal aqueous solution of the fully neutralized salt of - salt of mono-basic fatty soap acid, and ?ltering the amino acid is digested with the said fatty soap 65 the solution while hot to remove the excess mono vacid until the free alkali‘content of the aqueous basic fatty soap acid present therein. solution has been substantially removed there from by reaction with the said fatty acid to form FREDERICK C. BERSWORTH.