US 3811833 A
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AU 165 EX United States Patent [191 Stalter May 21, 1974 1 STABILIZED HYDROGEN PEROXIDE 2.740.689 4/1956 Easton et a1. 8/111 COMPOSITIONS CONTAINING 3,034,851 5/1962 Dustman, Jr 8/1 1 1 3,579,287 5/1971 Kowalski 252/99 AMMONlUM IONS, AND PROCESS FOR BLEACHING THEREWITH lnventor: Neil J. Stalter, Wilmington, Del.
E. l. dulont de Nemours and Company, Wilmington, Del.
Filed: June 30, 1972 Appl. No.: 268,05l
References Cited UNITED STATES PATENTS 6/1938 Colonius et a1 252/99 Primary Examiner-Mayer Weinblatt [5 7] ABSTRACT A stable aqueous bleaching composition comprising: (1) concentrated, acidic hydrogen peroxide stabilized with a stannate salt; (2) an ammonium salt; (3) a stabilizing amount of an organic acid, preferably an alkylidene diphosphonic acid or salt; (4) optionally, other additives. Upon making the bleaching composition alkaline, the Nl-l, ion is converted to ammonium hydroxide, which promotes the bleaching activity of hydrogen peroxide. There is also provided a process for bleaching with the bleaching composition.
9 Claims, No Drawings STABILIZED HYDROGEN PEROXIDE COMPOSITIONS CONTAINING AMMONIUM IONS, AND PROCESS FOR BLEACHING THEREWITH BACKGROUND OF THE INVENTION This invention relates to aqueous bleaching compositions and specifically to hydrogen peroxide compositions promoted by ammonium hydroxide.
Although hydrogen peroxide has long been known as a bleaching agent, it has never achieved significant acceptance for laundry usage and no hydrogen peroxide composition formulated for laundry bleaching usage, either domestic or industrial, is available commercially today. This is so notwithstanding the advantages which a liquid hydrogen peroxide bleach offers: convenient liquid form, ideal for use in cold water, compatible with all fabrics, effective on permanent-press finishes, compatible with most fabric softeners, certain germicides, and optical dyes, and satisfactory economics. The failme of hydrogen peroxide to find use as a laundry bleach is attributable in large measure to the fact that no chemical prmoting agent was available which could be formulated into the hydrogen peroxide solution by the manufacturer without causing precipitation of the stannate salts commonly used to stabilize acidic hydrogen peroxide as produced.
Most hydrogen peroxide'bleaching processes, e.g., textile, wood, hair, etc., and other oxidation reactions are carried out on the alkaline side. Furthermore, it has long been known that ammoniacal solutions of hydrogen peroxide possess unique stain removing character istics. Attempts to add ammonium salts to concentrated, acidic, stannate-stabilized hydrogen peroxide solutions (which would be diluted and made alkaline just prior to use) typically result in precipitation of the tin stabilizer, cloudy appearance and loss of stability. Thus, ther has been no convenient way to take advantage of the beneficial effect of ammonium hydroxide on hydrogen peroxide bleaching; it has heretofore been necessary to add liquid ammonium hydroxide to an alkaline bleaching solution immediately prior to use. This involves the additional diadvantage of filling the air with annoying and hazardous ammonia fumes.
SUMMARY OF THE INVENTION It has now been discovered that large concentrations of ammonium ions may be formulated into concentrated, acidic, stannate-stabilized hydrogen peroxide, which may optionally contain other additives, such as nitrates. Accordingly, the present invention provides a stable bleaching composition having a pH of about 0.5 to 7.0 and containing as essential ingredients in aqueous solution, based on the total weight of the composition, approximately: I to 50, preferably 25 to 50 percent hydrogen peroxide; 1 to 50 preferably 25 to 50 percent ammonium slat; 0.00l to 0.075 percent soluble stannate salt; 0.001 to 0.5 percent of an organic acid or salt selected from the group consisting of an alkylidene diphosphonic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and nitrilo trimethylene phosphonic acid; to 0.50 percent soluble nitrate salt; the remainder being water.
This composition will typically be diluted and made alkaline, thereby converting the ammonium salt to ammonium hydroxide, and is thus useful for any laundry bleaching purpose, as well as for numerous other bleaching purposes (e.g., wood, textile, etc.) Thus, the invention also includes a process for bleaching comprising admixing the bleaching composition with an alkalining agent in such quantity as to make the pH of the resulting admixture greater than 7.0 diluting the admixture to a level of 0.001 to 10 percent; preferably 0.002 to 0.5 percent and more preferably 0.005 to 0.03 percent hydrogen peroxide, and contacting a bleachable substance with the admixture. Since ammonia is considered essential for successful bleaching of human hair, this composition is also advantageous for that purpose. Furthermore, since the ammonium hydroxide is produced in situ, contamination of the air with ammonia fumes is minimized.
DETAILED DESCRIPTION OF THE INVENTION In forming the bleaching composition of the present invention, a soluble ammonium salt is added to concentrated hydrogen peroxide containing 0.001 to 0.075, preferably 0.005 to 0.075, percent by weight of a soluble stannate salt (usually Na SnO '3H,O), which acts as a stabilizer for the naturally acidic hydrogen peroxide and also containing 0.001 to 0.5, preferably 0.0] to 0.3 percent by weight of an organic acid such as an alkylidene diphosphonic acid such as is known by the trade name of Dequest 2010, manufactured by Monsanto Chemical Company. Suitable alkylidene diphosphonic acids are of the formula Where X is hydrogen or the hydroxyl radical and n is a whole number from 0 to 5. These acids are further described in copending application Ser. No. 49,946, filed June 25, 1970, the disclosure of which is incorporated herein by reference. Although the mechanism is not well understood, the diphosphonic acid is thought to act as a sequestrant and form a complex with the tin salt, thereby preventing the precipitation of the latter by the NH, ions. Other useful sequestrants include ethylenediaminetetracetic acid (EDTA), diethylenetriaminepentacetic acid (DTPA) and nitrilo trimethylene phosphonic acid (Dequest 2000"). Dequest 2 010" is preferred since it is exceptionally resistant to oxidation in H 0, solution in the presence of high concentrations of cations. The pH of such a hydrogen peroxide solution will be about 2.0 to 3.0 but, if desired, may be adjusted within the range of about 0.5 to 7.0 by the addition of common acidifying or alkalining agents such as phosphonic acid or caustic soda. For commercial expediency the hydrogen peroxide will usually be prepared as about 35 percent by weight, although concentrations of percent or more, or as low as l percent, may also be used without detracting from the effectiveness of the invention. The composition may also contain a soluble nitrate salt (e.g., sodium or ammonium nitrate) in a concentration of 0 to 0.50, preferably 0.001 to 0.07, percent. Such salts inhibit chloride corrosion of aluminum containers usually used to transport hydrogen peroxide. Suitable stannate salts include sodium stannate trihydrate, sodium metastannate and potassium stannate. The composition thus formed has excellent stability.
The NH, ion may be provided by any of numerous salts, such as ammonium sulfate, nitrate, acetate, chloride, citrate, phosphate, and formate. The ammonium salt may be added as crystals to the hydrogen peroxide solution, with stirring so as to effect dissolution. Preferably, however, the salt will be dissolved in an appropriate quantity of water and added to the hydrogen peroxide as a solution.
The bleaching composition may also advantageously contain any of various other chemicals whose uses are very familiar to the hydrogen peroxide art. Such chemicals include, for instance, sulfates (e.g., magnesium sulfate) and phosphates.
As has been mentioned, ammonium hydroxide is known to be an activator, presumably of the free amide type, for the bleaching action of hydrogen peroxide. Thus, when the bleaching composition of this invention is made alkaline, as is done in almost all bleaching applications, the NH., which functions as a stable latent hydrogen peroxide activator, is converted to ammonium hydroxide. Whereas the bleaching composition is quite stable in its acidic form, i.e., below about pH 7.0, when made alkaline, preferably about pH 9.0 to 11.0, the hydrogen peroxide is an active oxygen bleach whose effectiveness is significantly enhanced by the presence of the ammonium hydroxide. The composition can be made alkaline by any of the various common alkalining agents, such as soluble silicates and phosphates (e.g., the alkali phosphates), soda ash, bo-
rax, and caustic soda. One or more of these chemicals are usually present in common household laundry detergents. ln ordinary usage, for instance, in home laundering, the concentrated bleaching composition will be considerably diluted. For home usage the bleaching composition may be diluted to a hydrogen peroxide level of about 3 to 6 percent for sale to the consumer. An appropriate quantity of this would be added to the detergent cycle of the washing machine to produce preferably 20 to 100 ppm oxygen. The alkalinity available from the detergent composition being used would convert the NH, present to ammonium hydroxide.
The use of the bleaching composition has only a minor effect on the pH and total alkalinity of the common household detergents. Obviously, the bleaching composition may be utilized in more or less concentrated form, depending upon the usage, and separate alkalining agents may also be employed, if desired.
The ratio of NH, to H,O, is not critical, however, a 0.8 to 1.021 ratio is desirable. Thus, if the bleaching composition is formulated from standard commercial 35% H,O,, approximately 30 percent ammonium salt would be recommended. With a lower ratio the beneficial effect in the dilute alkaline wash solution would be proportionally reduced. A significantly high ratio would be precluded by the solubility of the ammonium salt in the 35% H,O,.
Temperature is not critical to the effectiveness of the bleaching composition; it may be employed in a socalled "cold wash as well as the normal hot wash. Useful temperatures cover the range of at least 50 to The invention is further illustrated by the following examples. Percentages are by weight.
EXAMPLE 1 To a commercial grade of hydrogen peroxide containing 35% H,O,, 0.1 percent Dequest 2010" and 0.01 percent sodium stannate was added, with stirring, 30 percent by weight of ammonium sulfate (NH,),SO,, the balance being water. When solution was complete the pH of the resulting solution was adjusted to 2.0 with nitric acid.
This solution was then heated at 212F. during a period of about 5 hours and stability was determined by the rate of gas evolution. The calculated loss in active oxygen for a 15 hour period was 1.8 percent. The stability of the commercial 35% H,O, is on the order of 0.5 to 3 percent loss in this test.
EXAMPLE 2 A solution of hydrogen peroxide was prepared as in Example 1. This solution was then diluted to a concentration of 5% H 0 The solution was heated in a flask immersed in a water bath at 212F. while preventing evaporation. Analysis of the solution at the end of a 24 hour period showed a loss of 2.3 percent, which is commercially satisfactory stability for the diluted product.
EXAMPLE 3 A solution was made up as described in Example 1 except that ammonium nitrate was used instead of ammonium sulfate. This solution was then diluted to 3% H,O and tested as in Example 2. The active oxygen loss in 24 hours at C. was 3.3%, which is commercially satisfactory stability for the diluted product. EXAMPLE 4 A solution was prepared, according to the procedure of Example 1, to have the following composition: 28% H,O,, 0.1 percent Dequest 2010, 20% (NH,),SO,, the balance being water. The pH was 2.3 initially; this was adjusted to 0.5 by addition of nitric acid.
This solution was heated at 159F. for 20 hours at which time the H,O, concentration had decreased to 26.6 percent from its initial value of 27.2 percent. EXAMPLE 5 A solution was prepared as in Example 4, to have the following composition: 5% H,O,, 0.1 percent Dequest 2010," 3% (NH ),S0,, the balance being water. The initial pH was 2.8; this was adjusted to 0.5 by addition of nitric acid.
After heating for 20 hours at 150F. the initial H,O, concentration of 4.9 percent had decreased to 4.8 percent.
EXAMPLE 6 Two samples of standard (EMPA) stained cloth (blood, milk and Japanese ink; original brightness of 10 Hunter units) were washed for 100 minutes at F. in a Launder-O-Meter, the wash solution containing 0.15 percent Tide" detergent plus 75 ppm Alkalase enzyme, and 30 ppm active oxygen as hydrogen peroxide. The control cloth, washed with no NH ions in the solution, showed an increase in Hunter brightness of 6.9 units. The other cloth, washed with ppm Nl-LOH in the wash solution, showed a Hunter brightness increase of 8.5 units.
1. A stable aqueous bleaching composition having a pH of about 0.5 to 7.0 and, based on the total weight of the composition, consisting essentially of: (1) about 1 to about 50 weight percent hydrogen peroxide; (2) about 1 to about 50 weight percent of a water soluble ammonium salt; (3) about 0.001 to 0.075 weight percent of a soluble stannate salt selected from the group (SEX Hah-H 011 wherein X is hydrogen or the hydroxyl radical and n is a whole number from 0 to 5.
2. A composition of claim 1 wherein the ammonium salt is selected from the group consisting of ammonium sulfate, nitrate, acetate, chloride, citrate, phosphate, and formate,
3. A composition of claim 1 containing approximately 25 to 50 percent hydrogen peroxide, 25 to 50 percent ammonium salt, 0.005 to 0.075 percent soluble stannate salt, 0.01 to 0.3 percent organic acid, and 0.001 to 0.07 percent soluble nitrate salt.
4. A composition of claim 1 wherein the organic acid is an alkylidene diphosphonic acid.
5. A process for bleaching comprising admixing (a) an aqueous bleaching composition having a pH of about 0.5 to 7.0 with (b) an alkalining agent selected from the group consisting of soluble phosphates, silicates, soda ash, borax and caustic soda to make the pH of the resulting admixture approximately 9 to 1 l, diluting the admixture to a level of 0.002 to 0.5 weight percent hydrogen peroxide, and contacting a substance which is capable of being bleached by hydrogen peroxide with the admixture, said aqueous bleaching composition, based on the total weight of the composition, consisting essentially of 1) about 1 to about 50 weight percent hydrogen peroxide; (2) about 1 to about 50 weight percent of a water soluble ammonium salt; (3) about 0.001 to about 0.075 weight percent of asoluble stannate salt selected from the group consisting of sodium stannate trihydrate, sodium metastannate, and potassium stannate; and (4) about 0.01 to about 0.3 weight percent of an alkylidene diphosphonic acid; the remainder being water, said alkylidene diphosphonic acid being of the formula i -on on cam-E on wherein X is hydrogen or the hydroxyl radical and n is a whole number from 0 to 5.
6. A process for bleaching comprising admixing a composition of claim 1 with an alkalining agent in such quantity as to make the pH of the resulting admixture greater than 7.0, diluting the admixture to a level of 0.001 to 10 percent, and contacting a substance which is capable of being bleached by hydrogen peroxide with the admixture.
7. A process of claim 6 wherein the hydrogen perox' ide level is about 0.002 to 0.5 percent hydrogen peroxide.
8. A process of claim 6 wherein the alkalining agent is selected from the group consisting of soluble phosphates, silicates, soda ash, borax, and caustic soda.
9. A process of claim 6 wherein the pH is approximately 9.0 to 11.0.
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