Bleaching and Laundering Composition Containing Magnesium Monoperoxyphthalate a Chelating Agent, a Peroxygen Compound and Phthalic Anhydride

The application is related to Ser. No. 329,534, filed Dec. 10, 1981, now U.S. Pat. No. 4,378,300 which describes a bleaching and laundering composition comprising a peroxygen compound, an activator therefor comprising phthalic anhydride, and diethylene triamine pentamethylene phosphonic acid and/or a water-soluble salt thereof.

This application is a continuation-in-part of copending application Ser. No. 379,824, filed May 20, 1982, the disclosure of which is hereby incorporated by reference.

This invention relates, in general, to bleaching and laundering compositions and their application to laundering operations. More specifically, this invention relates to bleaching and laundering compositions comprising monoperoxyphthalic acid and/or a water-soluble salt thereof, a chelating agent capable of forming a water-soluble metal complex in aqueous solution, a peroxygen compound and an organic activator for said peroxygen compound comprising phthalic anhydride.

Bleaching compositions which release active oxygen in the laundry solution are extensively described in the prior art and commonly used in laundering operations. In general, such bleaching compositions contain peroxygen compounds, such as, perborates, percarbonates, perphosphates and the like which promote the bleaching activity by forming hydrogen peroxide in aqueous solution. A major drawback attendant to the use of such peroxygen compounds is that they are not optimally effective at the relatively low washing temperatures employed in most household washing machines in the United States, i.e., temperatures in the range of 80.degree. to 130.degree. F. By way of comparison, European wash temperatures are generally substantially higher extending over a range, typically, from 90.degree. to 200.degree. F. However, even in Europe and those other contries which generally presently employ near boiling washing temperatures, there is a trend towards lower temperature laundering.

In an effort to enhance the bleaching activity of peroxygen bleaches, the prior art has employed materials called activators in combination with the peroxygen compounds. It is generally believed that the interaction of the peroxygen compound and the activator results in the formation of a peroxyacid which is the active species for bleaching. Numerous compounds have been proposed in the art as activators for peroxygen bleaches among which are included carboxylic acid anhydrides such as those disclosed in U.S. Pat. Nos. 3,928,775; 3,338,839; and 3,352,634; carboxylic esters such as disclosed in U.S. Pat. No. 2,995,905; N-acyl compounds such as those described in U.S. Pat. Nos. 3,912,648 and 3,919,102; cyanomines such as described in U.S. Pat. No. 4,199,466; and acyl sulfoamides such as disclosed in U.S. Pat. No. 3,245,913.

Pre-formed peroxyacids have also been used to effect bleaching in laundry was solutions. U.S. Pat. Nos. 3,770,816; 4,170,453; and 4,259,201 are illustrative of prior art disclosures relating to bleaching compositions comprising a peroxyacid compound.

It is generally recognized in the art that metal ions are capable of acting as decomposition catalysts for inorganic peroxygen compounds and organic peroxyacids. In an effort to stabilize such bleaching species in the wash solution, chelating agents have been incorporated into bleaching detergent compositions. U.S. Pat. No. 3,243,378 to Stoltz, for example, discloses a bleaching composition containing a peroxygen bleaching compound and a chelating agent to sequester metal cations. In general, the chelating agents which have been used for this purpose fall into one or two categories: (a) materials such as heterocyclic compounds and ketones, notably 8-hydroxyquinoline, which tie up metal cations in the laundry wash by precipitating them from solution; and (b) materials such as aminopolycarboxylates and aminopolyphosphonate compounds which form water-soluble metal complexes with the cations present in the wash solution. Accordingly, U.S. Pat. No. 4,005,029 discloses that selected aldehydes, ketones and compounds which yield aldehydes or ketones in aqueous solution (e.g., 8-hydroxyquinoline) can be used to activate aliphatic peroxyacids, such as, diperazelaic acid, diperadipic acid and aromatic peroxyacids (and water-soluble salts thereof) including monoperoxyphthalic acid and diperoxyterephthalic acid. In U.S. Pat. No. 4,170,453, a mixture of 8-hydroxyquinoline, phosphoric acid and sodium pyrophosphate is disclosed as a preferred chelating system to stabilize the active oxygen generated in wash solutions containing diperoxydodecandioic acid. U.S. Pat. No. 4,225,452 to Leigh discloses the combination of specified classes of chelating agents (among which are phosphonate compounds) with inorganic peroxygen compounds and an organic activator for the purpose of suppressing the decomposition of the peroxygen compound in the bleach composition. Specifically, the chelating agent is said to inhibit the unwanted side reaction of the peroxygen compound with the peroxyacid formed by the primary reaction of the peroxygen compound and the activator, the effect of the side reaction being to deplete the peroxyacid bleaching species from solution. The Leigh patent, however, discourages the use of such chelating agents in solutions wherein the peroxyacid has a double bond between the carbon atoms in the .alpha.,.alpha.' position to the carbonyl group. Specifically, at column 2 of the patent, beginning at line 63, the patentee excludes phthalic anhydride as an activator for the disclosed bleaching composition because of instability. Inasmuch as the peroxyacid formed by the reaction of phthalic anhydride and an inorganic peroxygen compound is monoperoxyphthalic acid, the Leigh patent apparently discourages the use of monoperoxyphthalic acid in the bleaching compositions of the patent.

European Patent Publication No. 0,027,693, published Apr. 29, 1981, discloses the use of magnesium monoperoxyphthalate as an effective bleaching agent. There is also disclosed the optional combination of a bleaching agent with an "aldehyde or ketone peroxyacid activator as described in U.S. Pat. No. 4,005,029, e.g., 8-hydroxyquinoline which is a known peroxygen stabilizer". The Publication also discloses organic phosphonate compounds, along with a wide variety of other compounds, as being useful detergent builders which optionally may be included in the described washing compositions. No disclosure is made, however, concerning the beneficial effects attendant to the use of a small amount of organic phosphonate compounds to serve as chelating agents in bleaching compositions and particularly, in compositions containing magnesium monoperoxyphthalate.

The aforementioned European Patent Publication also discloses that peroxygen compounds may optionally be included in the laundering compositions containing the described peroxyacid bleaching agents in order to provide bleaching at higher washing temperatures. However, no suggestion is made concerning the use of an organic activator in combination with such peroxygen compounds, and in particular, about the desirability of using a peroxygen compound in combination with phthalic anhydride as an activator in a bleaching system containing monoperoxyphthalic acid and/or a salt thereof and a chelating agent of the type herein described.

The present invention provides a bleaching composition comprising monoperoxyphthalic acid (also referred to herein as "MPPA" for purposes of convenience) and/or a water-soluble salt thereof, a chelating agent capable of forming a substantially water-soluble complex with metal ion in aqueous solution, a peroxygen compound and an organic activator for said peroxygen compound comprising phthalic anhydride.

The bleaching detergent composition of the invention comprises the above-defined bleaching composition in combination with a surface active detergent and one or more detergent builder salts. In accordance with the process of the invention, bleaching of stained and/or soiled materials is effected by contacting such materials with an aqueous solution of the above-defined compositions.

The term "chelating agent" as used herein refers to organic compounds which, in small amounts, are capable of binding transition metal cations, (e.g., iron, nickel and cobalt) which are known to adversely affect the stability of peroxygen compounds and/or peroxyacids in aqueous bleaching solutions. The chelating agents employed herein therefore exclude inorganic compounds ordinarily used in detergent formulations as builder salts. The chelating agents useful for the present invention are of the type capable of forming a substantially water-soluble, rather than a precipitated, metal complex in aqueous solutions with metal ions, most notably, transition metal cations such as those referred to above. Suitable chelating agents therefore include ethylene diamine tetraacetic acid (EDTA); nitrilotriacetic acid (NTA); diethylene triamine pentaacetic acid; ethylene diaminetetramethylene phosphonic acid (EDITEMPA); amino trimethylene phosphonic acid (ATMP); diethylene triamine pentacetic acid (DETPA), all of the above-mentioned compounds being preferably employed in the form of the sodium salt.

A preferred class of chelating agents are the organic phosphonate compounds such as those disclosed in U.S. Pat. No. 4,225,452, the formulae of which are set forth in Equations, I, II and III in columns 3 and 4 of the patent. Among this class of materials diethylene triamine pentamethylene phosphonic acid (referred to herein as "DTPMP"), and/or a water-soluble salt thereof is particularly preferred as a chelating agent for purposes of the present invention. Among the salts of DTPMP, the sodium, potassium and ammonium salts are generally preferred because of their relatively greater solubility and ease of preparation.

In general, the chelating agents employed in the bleaching compositions of the invention are present in a weight ratio relative to MPPA and/or its salts of from about 1:5 to about 1:50, and more preferably, from about 1:7 to about 1:20. In the built bleaching detergent compositions of the invention, the concentration of chelating agent is generally below about 5%, by weight, preferably below about 2%, by weight, and most preferably below about 1%, by weight, of such detergent compositions. The chelating agents may be utilized alone or in combination with one or more other chelating agents. Thus, for example, DTPMP may be advantageously employed in combination with EDTA in the compositions of the invention.

Monoperoxyphthalic acid and/or one or more of its water-soluble salts in combination with a peroxygen compound are the bleaching agents in the compositions of the invention. Although MPPA provides acceptable bleaching activity, it has the disadvantages of relatively poor stability when stored in admixture with other components ordinarily present in household detergent compositions. Hence, for purposes of stability, the magnesium salt of MPPA is preferably employed in the compositions of the invention, namely, magnesium monoperoxyphthalate. The alkali metal, calcium or barium alkaline earth and/or ammonium salts of MPPA may also be employed in the bleaching and laundering compositions herein described, although such salts are generally less preferred from the standpoint of stability than the aforementioned magnesium salt.

The production of MPPA is generally effected by the reaction of hydrogen peroxide and phthalic anhydride. The resultant MPPA can then be used to produce magnesium monoperoxyphthalate by reaction with a magnesium compound in the presence of an organic solvent. A detailed description of the production of MPPA and its magnesium salt is set forth on pages 7 to 10, inclusive, of European Patent Publication No. 0,027,693, published Apr. 29, 1981, the aforementioned pages 7 to 10 being incorporated herein by reference.

The peroxygen compounds useful in the present invention include compounds that release hydrogen peroxide in aqueous media, such as, alkali metal perborates, percarbonates, perphosphates and the like. Sodium perborate is particularly preferred because of its commercial availability.

The peroxygen compound is generally present in the bleaching composition relative to the phthalic anhydride activator in a molar ratio of peroxygen compound to phthalic anhydride of about 1:10 to about 10:1, the preferred ratio being from about 1:2 to about 3:1. It will be appreciated that the concentration of phthalic anhydride will depend on the concentration of the peroxygen compound, which in turn is governed by the degree of bleaching desired. The peroxygen compound is typically present in the bleaching composition in an amount ranging from about 1% to about 50%, by weight, preferably 3% to 25%, and most preferably, 5% to 20%, by weight, of the bleaching composition.

The amount of bleaching composition added to the wash solution is generally selected to provide an amount of peroxygen and peroxyacid compounds within the range corresponding to about 3 to 100 parts of active oxygen per million parts of the wash solution.

MPPA and/or water-soluble salt thereof in combination with the selected chelating point, peroxygen compound and phthalic anhydride may be formulated as a separate bleach product, or alternatively may be employed in a built detergent composition. Accordingly, the bleaching composition of the invention may include conventional additives used in the fabric washing art, such as, binders, fillers, builder salts, proteolytic enzymes, optical brighteners, perfumes, dyes, corrosion inhibitors, anti-redeposition agents, foam stabilizers and the like, all of which may be added in varying quantities depending on the desired properties of the bleaching composition and their compatibility with such composition. Additionally, the bleaching compositions of the invention may be incorporated into laundering detergent compositions containing surface active agents, such as, anionic, cationic, nonionic, ampholytic and zwitterionic detergents and mixtures thereof.

When the instant bleaching compositions are incorporated into a conventional laundering composition and are thus provided as a fully formulated bleaching detergent composition, the latter compositions will comprise the following: from about 5 to 50%, by weight, of the instant bleaching composition; from about 5 to 50%, by weight, of a detergent surface active agent, preferably from about 5 to 30%, by weight; and from about 5 to 80%, by weight, of a detergent builder salt which can also function as a buffer to provide the requisite pH range when the laundering composition is added to water. The aqueous wash solutions will have a pH range of from about 7 to 12, preferably from about 8 to 10, and most preferably from about 8.5 to 9. A preferred amount of the builder salt is from about 20% to about 65%, by weight, of the composition. The balance of the composition will predominantly comprise water, filler salts, such as, sodium sulfate, and optionally, minor additives, such as, optical brighteners, perfumes, dyes, anti-redeposition agents and the like.

Among the anionic surface active agents useful in the present invention are those surface active or detergent compounds which contain an organic hydrophobic group containing generally from about 8 to 26 carbon atoms and preferably 10 to 18 carbon atoms in their molecular structure and at least one water-solubilizing group selected from the groups of sulfonate, sulfate, carboxylate, phosphonate and phosphate so as to form a water-soluble detergent.

Examples of suitable anionic detergents include soaps, such as, the water-soluble salts (e.g., the sodium, potassium, ammonium and alkanolammonium salts) of higher fatty acids or resin salts containing from about 8 to 20 carbon atoms and preferably 10 to 18 carbon atoms. Suitable fatty acids can be obtained from oils and waxes of animal or vegetable origin, for example, tallow, grease, coconut oil and mixtures thereof. Particularly useful are the sodium and potassium salts of the fatty acid mixtures derived from coconut oil and tallow, for example, sodium coconut soap and potassium tallow soap.

The anionic class of detergents also includes the water-soluble sulfated and sulfonated detergents having an alkyl radical containing from about 8 to 26, and preferably from about 12 to 22 carbon atoms. Examples of the sulfonated anionic detergents are the higher alkyl mononuclear aromatic sulfonates such as the higher alkyl benzene sulfonates containing from about 10 to 16 carbon atoms in the higher alkyl group in a straight or branched chain, such as, for example, the sodium, potassium and ammonium salts of higher alkyl benzene sulfonates, higher alkyl toluene sulfonates and higher alkyl phenol sulfonates.

Other suitable anionic detergents are the olefin sulfonates including long chain alkene sulfonates, long chain hydroxyalkane sulfonates or mixtures of alkene sulfonates and hydroxyalkane sulfonates. The olefin sulfonate detergents may be prepared in a conventional manner by the reaction of SO.sub.3 with long chain olefins containing from about 8 to 25, and preferably from about 12 to 21 carbon atoms, such olefins having the formula RCH.dbd.CHR.sub.1 wherein R is a higher alkyl group of 6 to 23 carbons and R.sub.1 is an alkyl group containing from about 1 to 17 carbon atoms or hydrogen to form a mixture of sultones and alkene sulfonic acids which is then treated to convert the sultones to sulfonates. Other examples of sulfate or sulfonate detergents are paraffin sulfonates containing from about 10 to 20 carbon atoms, and preferably from about 15 to 20 carbon atoms. The primary paraffin sulfonates are made by reacting long chain alpha olefins and bisulfites. Paraffin sulfonates having the sulfonate group distributed along the paraffin chain are shown in U.S. Pat. Nos. 2,503,280; 2,507,088; 3,260,741; 3,372,188 and German Pat. No. 735,096. Other useful sulfate and sulfonate detergents include sodium and potassium sulfates of higher alcohols containing from about 8 to 18 carbon atoms, such as, for example, sodium lauryl sulfate and sodium tallow alcohol sulfate, sodium and potassium salts of alpha-sulfofatty acid esters containing about 10 to 20 carbon atoms in the acyl group, for example, methyl alpha-sulfomyristate and methyl alpha-sulfotallowate, ammonium sulfates of mono- or di-glycerides of higher (C.sub.10 -C.sub.18) fatty acids, for example, stearic monoglyceride monosulfate; sodium and alkylol ammonium salts of alkyl polyethenoxy ether sulfates produced by conducting 1 to 5 moles of ethylene oxide with 1 mole of higher (C.sub.8 -C.sub.18) alcohol; sodium higher alkyl (C.sub.10 -C.sub.18) glyceryl ether sulfonates; and sodium or potassium alkyl phenol polyethenoxy ether sulfates with about 1 to 6 oxyethylene groups per molecule and in which the alkyl radicals contain about 8 to 12 atoms.

The most highly preferred water-soluble anionic detergent compounds are the ammonium and substituted ammonium (such as mono, di and tri-ethanolamine), alkali metal (such as, sodium and potassium) and alkaline earth metal (such as, calcium and magnesium) salts of the higher alkyl benzene sulfonates, olefin sulfontes and higher alkyl sulfates. Among the above-listed anionics, the most preferred are the sodium linear alkyl benzene sulfonates (LABS).

The nonionic synthetic organic detergents are characterized by the presence of an organic hydrophobic group and an organic hydrophilic group and are typically produced by the condensation of an organic alphatic or alkyl aromatic hydrophobic compound with ethylene oxide (hydrophilic in nature). Practically any hydrophobic compound having a carboxy, hydroxy, amido or ammino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide or with the polyhydration product thereof, polyethylene glycol, to form a nonionic detergent. The length of the hydrophilic or polyoxyethylene chain can be readily adjusted to achieve the desired balance between the hydrophobic and hydrophilic groups.

The nonionic detergents include the polyethylene oxide condensate of 1 mole of alkyl phenol containing from about 6 to 12 carbon atoms in a straight or branched chain configuration with about 5 to 30 moles of ethylene oxide, for example, nonyl phenol condensed with 9 moles of ethylene oxide; dodecyl phenol condensed with 15 moles of ethylene oxide; and dinonyl phenol condensed with 15 moles of ethylene oxide. Condensation products of the corresponding alkyl thiophenols with 5 to 30 moles of ethylene oxide are also suitable.

Of the above-described types of nonionic surfactants, those of the ethoxylated alcohol type are preferred. Particularly preferred nonionic surfactants include the condensation product of coconut fatty alcohol with about 6 moles of ethylene oxide per mole of coconut fatty alcohol, the condensation product of tallow fatty alcohol with about 11 moles of ethylene oxide per mole of tallow fatty alcohol, the condensation product of a secondary fatty alcohol containing about 11-15 carbon atoms with about 9 moles of ethylene oxide per mole of fatty alcohol and condensation products of more or less branched primary alcohols, whose branching is predominantly 2-methyl, with from about 4 to 12 moles of ethylene oxide.

Zwitterionic detergents such as the betaines and sulfobetaines having the following formula are also useful: ##STR1## wherein R is an alkyl group containing from about 8 to 18 carbon atoms, R.sub.2 and R.sub.3 are each an alkylene or hydroxyalkylene group containing about 1 to 4 carbon atoms, R.sub.4 is an alkylene or hydroxyalkylene group containing 1 to 4 carbon atoms, and X is C or S:O. The alkyl group can contain one or more intermediate linkages such as amido, ether, or polyether linkages or non-functional substituents such as hydroxyl or halogen which do not substantially affect the hydrophobic character of the group. When X is C, the detergent is called a betaine; and when X is S:O, the detergent is called a sulfobetaine or sultaine.

Cationic surface active agents may also be employed. They comprise surface active detergent compounds which contain an organic hydrophobic group which forms part of a cation when the compound is dissolved in water, and an anionic group. Typical cationic surface active agents are amine and quaternary ammonium compounds.

Examples of suitable synthetic cationic detergents include: normal primary amines of the formula RNH.sub.2 wherein R is an alkyl group containing from about 12 to 15 atoms; diamines having the formula RNHC.sub.2 H.sub.4 NH.sub.2 wherein R is an alkyl group containing from about 12 to 22 carbon atoms, such as N-2-aminoethyl-stearyl amine and N-2-aminoethyl myristyl amine; amide-linked amines, such as those having the formula R.sub.1 CONHC.sub.2 H.sub.4 NH.sub.2 wherein R.sub.1 is an alkyl group containing about 8 to 20 carbon atoms, such as N-2-amino ethylstearyl amide and N-amino ethylmyristyl amide; quaternary ammonium compounds wherein typically one of the groups linked to the nitrogen atom is an alkyl group containing about 8 to 22 carbon atoms and three of the groups linked to the nitrogen atom are alkyl groups which contain 1 to 3 carbon atoms, including alkyl groups bearing inert substituents, such as phenyl groups, and there is present an anion such as halogen, acetate, methosulfate, etc. The alkyl group may contain intermediate linkages such as amide which do not substantially affect the hydrophobic character of the group, for example, stearyl amide propyl quaternary ammonium chloride. Typical quaternary ammonium detergents are ethyl-dimethyl-stearyl-ammonium chloride, benzyl-dimethyl-stearyl ammonium chloride, trimethyl-stearyl ammonium chloride, trimethyl-cetyl ammonium bromide, dimethyl-ethyl-lauryl ammonium chloride, dimethyl-propyl-myristyl ammonium chloride, and the corresponding methosulfates and acetates.

Ampholytic detergents are also suitable for the invention. Ampholytic detergents are well known in the art and many operable detergents of this class are disclosed by A. M. Schwartz, J. W. Perry and J. Birch in "Surface Active Agents and Detergents," Interscience Publishers, New York, 1958, vol. 2. Examples of suitable amphoteric detergents include: alkyl betaiminodipropionates, RN(C.sub.2 H.sub.4 COOM).sub.2 ; alkyl beta-amino propionates, RN(H)C.sub.2 H.sub.4 COOM; and long chain imidazole derivatives having the general formula; ##STR2## wherein in each of the above formulae R is an acyclic hydrophobic group containing from about 8 to 18 carbon atoms and M is a cation to neutralize the charge of the anion. Specific operable amphoteric detergents include the disodium salt of undecylcycloimidiniumethoxyethionic acid-2-ethionic acid, dodecyl beta alanine, and the inner salt of 2-trimethylamino lauric acid.

The laundry detergent composition of the invention optionally contain a detergent builder of the type commonly used in detergent formulations. Useful builders include any of the conventional inorganic water-soluble builder salts, such as, for example, water-soluble salts of phosphates, pyrophosphates, orthophosphates, polyphosphates, silicates, carbonates, and the like. Organic builders include water-soluble phosphonates, polyphosphonates, polyhydroxysulfonates, polyacetates, carboxylates, polycarboxylates, succinates and the like.

Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, pyrophosphates and hexametaphosphates. The organic polyphosphonates specifically include, for example, the sodium and potassium salts of ethane 1-hydroxy-1,1-diphosphonic acid and the sodium and potassium salts of ethane-1,1, 2-triphosphonic acid. Examples of these and other phosphorous builder compounds are disclosed in U.S. Pat. Nos. 3,213,030; 3,422,021; 3,422,137 and 3,400,176. Pentasodium tripolyphosphate and tetrasodium pyrophosphate are especially preferred water-soluble inorganic builders.

Specific examples of non-phosphorous inorganic builders include water-soluble inorganic carbonate, bicarbonate and silicate salts. The alkali metal, for example, sodium and potassium, carbonates, bicarbonates and silicates are particularly useful herein.

Water-soluble organic builders are also useful. For example, the alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxysulfonates are useful builders for the compositions and processes of the invention. Specific examples of polyacetate and polycarboxylate builders include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylene diaminetetracetic acid, nitrilotriacetic acid, benzene polycarboxylic (i.e. penta- and tetra-) acids, carboxymethoxysuccinic acid and citric acid.

The bleaching compositions of the invention are prepared by admixing the ingredients as hereinafter illustrated. When preparing laundering compositions containing the bleaching composition in combination with a surface active detergent compound and/or builder salts, the components of the bleaching composition can be mixed directly with the detergent compound, builder and the like. Alternatively, the peroxygen activator, the MPPA and the peroxygen compound can be coated with a coating material to improve stability and/or prevent premature activation of the bleaching agent. The coating process is conducted in accordance with procedures well known in the art. Suitable coating materials include compounds such as magnesium sulfate, polyvinyl alcohol, lauric acid or its salts and the like.

Bleaching tests were carried out on standard stained test swatches (described below) using the various bleaching and laundering compositions described in table 1 of this Example in a Tergotometer vessel manufactured by the U.S. Testing Company. The Tergotometer was maintained at a constant temperature of 120.degree. F. and operated at 100 rpm.

Each of the test compositions described in Table 1 below was added to one liter of tap water at 120.degree. F. having a water hardness of about 100 ppm, as calcium carbonate. The test compositions were agitated for about one minute and then a mixed fabric load consisting of two swatches each (3".times.4") of the stained fabrics described below was added to each wash receptacle. After a 15 minute wash at 120.degree. F., the test fabrics were rinsed in 100.degree. F. tap water and then dried. The percent stain removal was measured by taking a reflectance reading for each stained test swatch prior to and after the washing using a Gardner Color Difference Meter, and the percent stain removal (% S.R.) was calculated as follows: ##EQU1## wherein "Rd before washing" represents the Rd value after staining.

The value of percent stain removal calculated for all five cloths were averaged for each test laundering composition. A difference greater than 2% in the average of the five stained cloths tested is considered significant.

At the end of each wash, the active oxygen content of the wash solution was determined by acidification with dilute sulfuric acid followed by treatment of the wash solution with potassium iodide and a minor amount of ammonium molybdate, and thereafter titration with standardized sodium thiosulfate using starch as the indicator.

The respective stains and test swatches were as follows:

Stained test cloths 1 and 2 are prepared by passing rolls of unsoiled fabric through a padding and drying apparatus (manufactured by Benz of Zurich, Switzerland) containing either grape or blueberry solutions at 90.degree. F. After drying at 250.degree. F., the fabric is cut into 3".times.4" swatches. Eighty of these swatches, impregnated with the same stain, are rinsed in 17 gallons of 85.degree. F. water in an automatic home washer. They are then dried by a passage through a Beseler Print Dryer at a machine temperature setting of 6 and a speed of 10.

Stained fabrics 3 and 4 are purchased from Testfabrics Incorporated of Middlesex, N.J., and cut into 3".times.4" swatches.

Stained fabric 5 is prepared by agitating and soaking unsoiled cotton strips (18".times.36") in a washing machine filled with a solution of coffee/tea (8:1 weight ratio) at 150.degree. F. The machine is allowed to rinse-spin dry to remove the coffee/tea solution. The stained fabric is then machine washed twice with hot pyrophosphate-surfactant solution followed by two complete water wash cycles at 140.degree. F. The strips are then dried by two passes through an Ironrite machine set at 10 and then cut into 3".times.4" swatches.

A granular detergent composition (designated herein as "HDD") was prepared by conventional spray-drying and had the following approximate composition:

Detergent compositions A-D containing HDD were formulated as set forth in Table 1.

Compositions A through D were tested in accordance with the procedure described above and the results of the bleaching tests are tabulated in Table 2 which sets forth the initial and final values of the active oxygen (A.O.) in the wash solution (expressed as "initial grams" and "residual grams", respectively) and the stain removal achieved for each of the 5 stains. T1 TABLE 2- Comparative Bleaching Performance? -Composition ? -? A B C D? -Initial grams 32.8 28.7 28.7 28.7 -(A.O. .times. 10.sup.3) -Residual grams 30.4 12.4 19.5 19.9 -(A.O. .times. 10.sup.3) -Grams consumed 2.4 16.3 9.2 8.8 -(A.O. .times. 10.sup.3)? -Stain Removal % % % %? -Grape 61 63 67 67 -Blueberry 56 65 67 68 -Sulfodye (EMPA 115) 3 4 4 4 -Red Wine (EMPA 114) 41 46 49 53 -Coffee/Tea 26 30 39 40 - Avg. (%) 37 42 45 46? -

The results of Table 2 indicate that compositions C and D consume substantially less active oxygen while providing improved stain removal relative to composition B, a composition similar to C and D except that it does not contain chelating agent DTPMP.

Detergent compositions E-J were formulated to contain 0.15% detergent concentration as shown below in Table 3.

Compositions E through J were tested in accordance with the procedures described in Example 1 and the results of the bleaching tests are tabulated in Table 4, the initial and final values of the active oxygen in the wash solution and the stain removal achieved for the five indicated stains being expressed as in Table 2 of Example 1.

The results of Table 4 indicate that the bleaching performance provided by composition G is improved when using compositions I and J in accordance with the invention which contain a reduced amount of the MPPA bleaching component relative to F and G but which additionally contain perborate and phthalic anhydride activator. Further, a comparison of the performance of I and J indicates that composition I provides equivalent bleaching effectiveness relative to composition J while consuming substantially less active oxygen, compositions I and J being identical except for the presence of DTPMP in the former and EDTA in the latter.