US3827868A - Cleanser compositions containing both oxidizing and reducing agents - Google Patents

Abstract

THIS DISCLOSURE RELATES TO SOLID ABRASIVE CLEANING COMPOSITIONS HAVING PARTICULAR UTILITY AS BOTH A TEA STAIN AND ALUMINUM POT MARK REMOVER FROM HARD SURFACES SUCH AS PORCELAIN, COMPRISING AN OXIDANT CAPABLE OF OXIDIZING THE METAL IN A PRICTICAL TIME SUCH AS THE METALLIC IONS FURRIC, STANNOUS, CUPRIC AND MERCURIC, A REDUCTANT SUCH AS SODIUM HYPOPHOSPHITE CUPROUS CHLORIDE, AND AN ABRASIVE, SAID COMPOSITION HAVING A PH OF LESS THAN 2. ADDITIVES SUCH AS DETERGENTS, PERFUMES, FILLER, COLORANTS, ETC. MAY BE INCLUDED PROVIDED THEY DO NOT ADVERSELY EFFECT THE STAIN REMOVING PROPERTIES OF THE COMPOSITION. ALTHOUGH ALUMINUM POT MARKS ARE MOST OFTEN ENCOUNTERED IN NORMAL HOUSEHOLD CLEANING, SAID CLEANSERS ARE EFFECTIVE AGAINST OTHER METALLIC STAINS SUCH AS IRON, TIN, MAGNESIUM, ETC.

Description

United States Patent Office 3,827,868 Patented Aug. 6, 1974 U.S. Cl. 51-308 9 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to solid abrasive cleansing compositions having particular utility as both a tea stain and aluminum pot mark remover from hard surfaces such as porcelain, comprising an oxidant capable of oxidizing the metal in a practical time such as the metallic ions ferric, stannous, cupric and mercuric, a reductant such as sodium hypophosphite cuprous chloride, and an abrasive, said composition having a pH of less than 2. Additives such as detergents, perfumes, fillers, colorant-s, etc. may be included provided they do not adversely effect the stain removing properties of the composition. Although aluminum pot marks are most often encountered in normal household cleaning, said cleansers are effective against other metallic stains such as iron, tin, magnesium, etc.

This is a continuation, of application Ser. No. 668,669 filed Sept. 18, I1967 and now abandoned.

This invention relates to compositions particularly adapted for removal of both tea stains and aluminum pot marks from porcelain or ceramic surfaces.

There are many household cleansers on the market adapted for use either to remove metallic stains or tea stains. This situation has developed due to the different requirements for removal of each type of stain. More specifically, tea stains are removed either in acid medium such as oxalic acid, or in basic medium such as sodium hypochlorite; whereas aluminum pot marks are removed by abrasive action alone or combined with high alkalinity. Removal of aluminum marks, except by abrasive action, always involves oxidation (high alkalinity results in oxidation). Tea stain removal also involves oxidation. Both types of stains can be removed either under conditions of high alkalinity (pH above 12) or high acidity (pH below However, at the usable pH region (p'H 7 to 1'1), there is only tea stain removal and no aluminum stain removal.

At acid pH below 4 there is aluminum stain removal, but 0 no tea stain removal. Thus, in low pH systems where aluminum removal can be obtained, tea stain removal must be accomplished by a different mechanism (not oxidation) either chelation or reduction. In addition, rust stains require very strong acid for effective removal, for example 30% by weight sulfuric acid. This is dangerous for normal household cleaning, since it can irritate or burn the skin upon contact as well as cause irritating fumes to be inhaled. Still another disadvantage in the use of strong acids is to the ceramic surface itself which may become etched and marred whereby future stains are rendered more difficult to remove. As the sink or like fixture becomes old and more damaged from use, the difficulty of removing stains from said ceramic surfaces is increased. A good stain removal cleanser must be effective in a very short time because in normal use the contact time between the cleanser and the stain is much less "than a minute. The complete removal of the stain depends on the condition of the surface, the severity of the stain, and the speed of the removal system. Thus, it is apparent that it has been difiicult to formulate a cleanser effective in the removal of both tea stains and metallic stains and which is safe for the housewife to use.

It has now been found that aluminum pot marks and other metallic stains such as iron as well as tea stains can be effectively removed in a practical time from porcelain or ceramic surfaces, by the conjoint chemical and mechanical action of a solid composition containing as the essential ingredients an oxidant, a reductant and an abrasive. The oxidant must be a system capable of converting the metal in the stain to a higher oxidation state in a practical time. The mechanism of the chemical reaction in the case of aluminum pot marks, is the conversion to .Al or some other soluble form of the ion, which is readily removed by the mechanical action of the abrasive. The reducing agent must be capable of reducing ferric in the tea stain to ferrous, which is also readily removed by the abrasive action.

More specifically, the solid cleansing composition for removal of metallic and tea stains from hard surfaces comprises a metallic salt oxidant, a reductant and an abrasive, maintained at a pH of less than 2. The pH is determined by a desire to avoid irritation to housewives hands, and still obtain an effective st-ain removing cleanser.

The oxidant ingredient must be capable of oxidizing the metal in the stain such as aluminum, in a practical time. Suitable metallic ions are those with higher oxidation potentials such as ferric, stannous, cupric, mercuric, auric and silver. The most efiective metallic salt is mercuric chloride, followed by cupric chloride, stannous chloride, ferric chloride, auric chloride and silver nitrate. The most efiective metallic salt, mercuric, is unique because it forms a liquid metal, but its ability to remove aluminum stains is not due to the formation of a liquid metal. Metallic ions with oxidation potentials closer to aluminum are probably effective over a long time period but for removal of aluminum stains in a practical time, ferrous ion was only marginally effective and zinc ion showed little or no reaction. Non-metallic oxidants, such as sodium perchlorate and potassium iodate show margin-a1 removal at the desired use pHs. These latter oxidants reactant more rapidly in stronger acid solutions, which is undesirable for household use. The hydrogen ion itself is an effective oxidant and assists in the oxidation of the met-a1 stain. Hydrogen peroxide was found to be moderately effective. The amount of oxidant found effective herein constitutes about -4-'10% by weight of the total composition.

Halides, particularly the chloride promote aluminum mark removal, but are not necessary. The halide activates the metallic salt oxidant whereby stain removal is increased, whereas other anions such as nitrates and sulfates tend to inhibit aluminum removal. Thus, it is apparent that anion effects must be considered and tested when formulating a complete cleanser.

Compounds may be utilized which are capable of performlng more than one function such as cupric chloride, stannous chloride, ferric chloride and auric chloride which combine the oxidant and promoter in a single compound.

The reducing agent, another essential ingredient in the instant composition, must be capable of reducing the ferric ion in the tea stain to ferrous in a practical time. Suitable reductants include water soluble metallic salts of hypophosphite such as sodium hypophosphite, and cuprous chloride. The cuprous chloride is unique in that it acts both as an oxidizing agent for the removal of aluminum marks and as a reducing agent for the removal of tea stains. The amount of reductant is preferably equivalent in weight to the amount of oxidant, about 4-10% by weight of the total composition.

The pH of the cleansing composition must be maintained below 2, since tea stain removal performance (by reduction) drops off rapidly at pH 2. The preferred pH for effective reducing action is about 1. Fluorides and complex fluorides improve aluminum mark removal and remove tea stains but at the effective pH (about 1) attack the procelain enamel surface. The pH range is also determined by the acid concentration suitable for use in a general household product. More specifically the lower limit is the point beyond which the porcelain enamel surface is attacked and the housewifes hands are irritated. The upper pH limit is limited by the efficiency of the reductant. Any suitable acid which does not react with the oxidant or reductant, may be utilized to maintian the desired pH. However, a solid acid such as sulfamic acid is preferred when formulating a solid product. Most solid organic carboxylic acids would not be satisfactory for a variety of reasons. They may be too weak to effect proper pH control. They may preciptate, complex or chelate with the metallic salt oxidant. Accordingly, a strong solid acid such as sulfamic acid, sodium bisulfate, trichloroacetic acid, in amounts sufficient to maintain a pH of less than 2 are preferred in the instant cleanser.

The abrasive must be combined with the metallic oxidant and reductant ingredients to insure the mechanical removal of the appropriate metals that normally deposit on the stains during the oxidation and reduction reactions. This frees the aluminum surface for further oxidation reaction via the metallic oxidant and frees the ferric ion in the tea stain for further reduction to the ferrous ion, as well as adding its own abrasive action. Any abrasive may be employed inclusive of silex (silica flour), feldspar, ground quartz, pumice, chalk, tripoli, kieselguhr, diatomaceous earth, etc. Silex is preferred because it can be obtained in the form of a fine powder, although any other finely divided abrasive material may be utilized. The abrasive ingredient constitute about 80-94% by weight of the composition.

This cleansing composition may include other ingredients such as surface active agents (anionic, cationi and non-ionic) perfumes, fillers, diluents, colorants, etc. useful in household cleansers in widely varying proportions. However, where additives are used they should be selected and proportioned so as not to adversely affect the stain removal property of the composition.

Any suitable water-soluble organic surface agent which is non-reactive with the metal salt oxidant and the reductant ingredients may be utilized. The non-ionic detergents are preferred since they are completely non-reactive with the heavy metal ions of the oxidant ingredient. Suitable non-ionic detergents include the alkylene oxide condensation products of hydrophobic compounds such as ethylene oxide condensates with higher fatty acids, higher fatty acid amides, higher fatty alcohols or alkyl aryl hydrocarbons, having at least 5 and usually from 5 to 30 ethoxy groups per molecule i.e. coconut fatty acid monoethanol amide ethoxylated with 2 moles ethylene oxide, octyl phenoxy polyethoxy ethanol having moles ethylene oxide.

The cationic quaternary compounds may also be uti lized herein, since they do not adversely afiect the oxidizing action of the metallic salt. Suitable cationic detergents include the quaternary ammonium compounds such as stearyl dimethyl benzyl ammonium chloride, N-difatty dimethyl quaternary ammonium chloride, i.e. N-distearyl dimethyl ammonium chloride.

The anionic detergents tend to react with the heavy metal ions, thereby reducing the efficacy of the cleanser. However, the phosphate esters such as the sodium salt of phosphate nonyl phenol condensed with 6 moles of ethylene oxide, has been found to be operable in this system. Other anionics can be used provided they do not react to form an insoluble product or a complex which ties up the metal ion. Thus, it is apparent, that the surface active agent utilizable herein, must not react with the heavy metal ion to remove the latter from being effective in the present oxidizing system.

The stain-removing ingredients of the instant invention which comprise essentially a metallic salt oxidant, a reductant and an abrasive is normally in the form of an abrasive scouring powder. The use of both an oxidizing agent and a reducing agent in the same composition gives a potential problem of reaction with one another either during storage or use. Accordingly, it is preferred that the cleansing product be a solid rather than a liquid to afford stability to the composition and prevent loss of its stain removal properties resulting from the interreaction of the two active ingredients (the oxidant and reductant) during storage. The absence of a liquid medium, particularly water, permits the solid composition to maintain its maximum stain removing properties until actual usage thereof. However, a liquid composition may be possible by the inclusion of an additional reducing agent as a sacrificial inhibitor. More specifically, cuprous chlo ride could be used in a liquid system if cuprous is protected from its slow oxidation by air, either by elimination of air from the product or the inclusion of another reducing agent such as sodium bisulfite as a sacrificial inhibitor. This in turn necessitates the use of an excess of the oxidant so that a sufiicient amount remains after interreactant of the oxidant with the sacrificial reductant, for adequate stain removal. Thus, it is apparent that although a liquid composition is possible, a solid cleanser is preferred for reasons of stability.

The following examples are illustrative of the invention and it will be understood that the invention is not limited thereto.

EXAMPLE I Ingredients: Weight percent Cuprous chloride 5 Sulfamic acid 3.8 Lauryl diethanol amide 2 Heliogen blue 0.05 Perfume 0.25 Silex 88.9

This composition in the form of a 50% aqueous slurry (to simulate household cleaning), having a pH of 1.3 was tested for dynamic aluminum stain removal of aluminum by utilizing a toothbrush machine with a back and forth motion and an approximate 3 inch throw. The toothbrush head was weighted with a 1 lb. Weight using 50 strokes per 30 seconds on an etched porcelain white tile stained with aluminum pot marks. This composition resulted in aluminum stain removal.

This composition was also tested for tea stain removal by utilizing a static test, whereby a white porcelain etched tile stained with tea is contacted therewith for 15 seconds and 60 seconds. This static test resulted in 30% tea stain removal after 15 seconds and 80% stain removal after contact for 60 seconds. There was also visual evidence of some rust removal in the one-minute static test.

EXAMPLE II A composition containing 4% CuCl, 2% Na SO and 94% silex, at pH of 1.3 gave tea stain removal in the 30 second static test described in Example I. However, when the pH was raised to 2, the composition exhibited no tea stain removal.

EXAMPLE III A composition containing 5% NaH PO -H O and 4% CuCl at a pH of 1.3 gave 60% tea stain removal in the aforedefined 30 second static test.

EXAMPLE IV Ingredients: Weight percent Cupric chloride dihydrate 5 Sodium hypophosphite monohydrate 5 Sulfamic acid 1.8 Lauryl diethanol amide 2.0 Heliogen blue 0.05 Perfume 0.25 Silex 85.9

This composition which has a pH of 1.3 was made into a 50% aqueous slurry and tested for aluminum stain removal utilizing the same dynamic test as in Example I, resulted in 85% aluminum stain removal. In addition, this cleanser gave 85% tea stain removal in the 60 second static test.

EXAMPLE V Diatomaceous earth was substituted for the silex ingredient of Example I, and resulted in a cleanser of superior tea and aluminum stain removing properties.

EXAMPLE VI A cleanser composition formulated in accordance with Example II except that chalk was substituted for the silex, resulted in an excellent stain removing composition.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therefor without departing from the principles and true spirit of the invention.

I claim:

1. A solid composition for removing both a metallic stain and tea stains from ceramic surfaces and being nonirritating to human hands when in aqueous media consisting essentially of a major amount of an abrasive and minor amounts in a ratio of 1:25 to 25:1 of

(1) an ionic oxidant for said metallic stain selected from the group consisting of hydrogen peroxide and metallic salts having a higher oxidation potential than the metal of said metallic stain, and being selected from the group consisting of mercury, copper, tin, iron, gold and silver and (2) a water-soluble salt reductant capable of reducing ferric ion to ferrous and being selected from the group consisting of water soluble metallic salts of hypophosphite and cuprous chloride, said composition having a pH in water of about 1 and less than about 2.

2. A composition in accordance with claim 1 wherein the oxidant is a metallic salt, said metallic ion having a higher oxidation potential than aluminum.

3. A composition in accordance with claim 1 wherein said metallic salt of hypophosphite is sodium hypophosphite.

4. A composition in accordance with claim 1, wherein both the oxidant and reductant is cuprous chloride.

5. A composition in accordance with claim 2, wherein the oxidant is a metallic chloride.

6. A composition in accordance with claim 1, which also contains a water-soluble organic surface active agent non-reactive with the oxidant and reductant ingredients.

7. A composition in accordance with claim 1, wherein a solid acid, non-reactive with the oxidant and reductant ingredients, is added to maintain a pH of less than 2.

8. A composition in accordance with claim 7, wherein the acid is sulfamic acid.

9. A composition in accordance with claim 1, wherein the abrasive is silex.

References Cited Monick s1 294 DONALD J, ARNOLD, Pastr Examiner US. Cl. X.R. 51-307; 106-3