GB2138040A - Bleaching and laundering composition free of water-soluble silicates - Google Patents

Abstract

An improved particulate bleaching detergent composition is provided comprising (a) a bleaching agent comprising an inorganic peroxygen compound in combination with an activator therefor; and (b) at least one surface active agent selected from the group consisting of anionic, cationic, nonionic, ampholytic and zwitterionic detergents; said bleaching detergent composition being substantially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise an activator for a peroxygen compound, a water-insoluble silicate compound and a nonionic surfactant.

Description

SPECIFICATION ~ Bleaching and laundering composition free of water-soluble silicates The present invention relates, in general, to bleaching detergent compositions containing as a bleaching agent a peroxygen compound in combination with an organic activator therefor, and the application of such compositions to laundering operations. More particularly, the present invention relates to granular bleaching detergent compositions which provide enhanced bleaching performance concomitant with a significant improvement in the stability of the peroxyacid bleaching species in the wash solution.

Bleaching compositions which release active oxygen in the wash 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 to 130"F (27 to 54"C). By way of comparison, European wash temperatures are generally substantially higher extending over a range, typically, from 90 to 200"F (32 to 93"C).

However, even in Europe and those other countries which generally presently employ near boiling washing temperatures, there is a trend towards lower temperatures 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 compound. It is generally believed that the interaction of the peroxygen compound and the activator results in the formation of a peroxyacid which is a more active bleaching species than hydrogen peroxide at lower temperatures. 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. Patent Nos. 3,298,775; 3,338,839; and 3,532,634; carboxylic esters such as those disclosed in U.S. Patent No. 2,995,905; N-acyl compounds such as those described in U.S. Patent Nos. 3,912,648 and 3,919,102; cyanoamines such as described in U.S. Patent No. 4,199,466; and acyl sulphoamides such as disclosed in U.S. Patent No. 3,245,913.

The formation and stability of the peroxyacid bleaching species in bleach systems containing a peroxygen compound and an organic activator has been recognized as a problem in the prior art. U.S. Patent No. 4,255,452 to Leigh, for example, specifically addresses itself to the problem of avoiding the reaction of peroxyacid with peroxygen compound to form what the patent characterizes as "useless products, viz. the corresponding carboxylic acid, molecular oxygen and water". The patent states that such side-reaction is "double deleterious since peracid and percompound . . . are destroyed simultaneously". The patentee thereafter describes certain polyphosphonic acid compounds as chelating agents which are said to inhibit the abovedescribed peroxyacid-consuming side reaction and provide an improved bleaching effect.In contrast with the use of these chelating agents, the patentee states that other more commonly known chelating agents, such as, ethylene diamine tetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) are substantially ineffective and do not provide improved bleaching effects.

Accordingly, a disadvantage of the bleaching compositions of the Leigh patent is that they necessarily preclude the use of conventional sequestrants, many of which are less expensive and more readily available than the disclosed polyphosphonic acid compounds.

The influence of silicates on the decomposition of peroxyacid in the wash and/or bleaching solution has heretofore gone unrecognized in the art. U.S. Patent Nos. 3,860,391 and 4,292,575 disclose that silicates are conventionally employed as additives to peroxidecontaining bleaching solutions for the purpose of stabilizing peroxide compounds therein.

However, the patentees note the fact that the use of silicates in such bleaching solutions may create other problems in the bleaching operations, such as, the formation of silicate precipitates which deposit on the bleached goods. Consequently, the patents are directed to processes for bleaching cellulose fibre with silicate-free bleaching solutions in which peroxide stability is enhanced with compounds other than silicates.

European Patent Publication No. 0,028,432, published 13th May, 1981, discloses a granular laundry composition containing, among other things, a water-insoluble silicate and an organic activator compound for a peroxygen bleach. The pH characteristics of such laundry composition are said to be critical, specifically, the pH in a 2% aqueous dispersion being from 2 to 9, and preferably from 4 to 7. At page 7 of the publication there are described certain polyphosphonic acid compounds as being highly preferred components of the composition, the publication stating in this regard that the polyphosphonates "have been found to be uniquely effective in stabilizing organic peroxy-acids against the generally deleterious effect of water-insoluble silicates, especially those belonging to the zeolite and kaolin classes'. The nature of such "deleterious effect" is not specified.At page 38 of the publication granular laundry compo sitions are disclosed in Examples Vlil to X which do not contain sodium silicates, all of such compositions being shown to contain Dequest 2041 (ethylenediamine tetramethylene phosphonic acid). The compositions of the aforementioned Examples also contain a peroxygen compound activator which is incorporated into agglomerate particles consisting of the said activator, a water-insoluble silicate compound and a nonionic surfactant.

The present invention provides a particulate bleaching detergent composition comprising: (a) a bleaching agent comprising a peroxygen compound in combination with an activator thereof; and (b) at least one surface active agent comprising an anionic, cationic, nonionic, ampholytic or zwitterionic detergent or a mixture thereof; the said bleaching detergent composition being substantially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise an activator for a peroxygen compound, a water-insoluble silicate compound and a nonionic surfactant.

In accordance with the process of the present invention, bleaching of stained and/or soiled materials is effected by contacting such materials with an aqueous solution of the above-defined bleaching detergent composition.

The present invention is predicated on the discovery that the undesired loss of peroxyacid in the aqueous wash solution by reaction of peroxyacid with a peroxygen compound (or more specifically, hydrogen peroxide formed from such peroxygen compound) to form molecular oxygen is markedly reduced in bleaching systems which are substantially free of water-soluble silicate compounds. Although the applicants do not wish to be bound to any particular theory of operation it is believed that the presence of water-soluble silicates in peroxygen compound/activator bleach systems catalyzes the aforementioned reaction of peroxyacid with hydrogen peroxide which results in the loss of active oxygen from the wash solution which would otherwise be available for bleaching.It has been recognized in the art that metal ions, such as, for example, ions of iron and copper serve to catalyze the decomposition of hydrogen peroxide and also the peroxyacid reaction with hydrogen peroxide. However, with regard to such metal ion catalysis, the applicants have surprisingly discovered that conventional sequestrants, such, EDTA or NTA, which the prior art has deemed to be ineffective for inhibiting the aforementioned peroxyacid-consuming reaction (see, for example, the statement in column 4 of U.S. Patent 4,225,452) can be incorporated into the compositions of the present invention to stabilize the peroxyacid in solution.

The term "water-soluble silicate compounds" refers to compounds such as sodium silicate which are substantially soluble in aqueous laundering solutions and commonly present in conventional bleaching detergent compositions, but are substantially eliminated from the compositions of the present invention. The present invention contemplates, however, incorporating substantially water-insoluble silicates, most notably, alumino-silicate materials such as clays and zeolites into the bleaching detergent compositions described herein, water-soluble silicate compounds being considered fare more detrimental to peroxyacid stability than water-insoluble materials such as alumino-silicates.

In a preferred embodiment of the invention, the bleaching compositions described herein additionally contain a sequestering agent to enhance the stability of the peroxyacid bleaching compound in solution by inhibiting its reaction with hydrogen peroxide in the presence of metal ions. The term "sequestering agent" as used herein refers to organic compounds which are able to form a complex with Cu2+ ions such that the stability constant (pK) of the complexation is equal to or greater than 6 in water at 25"C at an ionic strength of 0.1 mole/litre, pK being conventionally defined by the formula: pK = - log K wherein K represents the equilibrium constant. Thus, for example, the pK values for complexation of copper ion with NTA and EDTA at the stated conditions are 1 2.7 and 18.8 respectively.The term "sequestering agent is therefore used herein in a sufficiently restrictive sense to exclude inorganic compounds commonly used in detergent formulations as builder salts. Especially useful sequestering agents include EDTA, diethylene triamine pentaacetic acid (DEPTA) and the various phosphonate sequestrants marketed by Monsanto Company under the trademark Dequest, e.g. Dequest 2000, 2006, 2041, 2051 and 2060.

In accordance with another embodiment of the present invention, the described bleaching compositions are further distinguished from certain water-soluble silicate free compositions disclosed in the art by restricting the use of sequesting agents in the bleaching compositions of the present invention to those having a stability constant no greater than about 20 for Cu2+ complex formation in water at 25"C and at an ionic strength of 0.1 mole/litre. This limitation necessarily precludes the presence of polyphosphonic acid compounds such as Dequest 2041 (ethylene diamine tetramethylene phosphonic acid) and Dequest 2060 (diethylene triamine pentamethylene phosphonic acid) in the bleaching compositions of the present invention, the aforementioned sequestrants having stability constants above about 20. Accordingly, suitable sequestering agents for this embodiment of the invention include the sodium salts of nitrilotriacetic acid (NTA); ethylene diamine tetraacetic acid (EDTA); ethylene diamine; tetramine, i.e.

(N-(CH2-CH2-N H2)3; bis(aminoethyl) glycolether-N N N'N'-tetraacetic acid (EGTA); and N(CH2-PO3H2)3 which is marketed under the tradename Dequest 2000. EDTA and the aforementioned Dequest 2000 are especially preferred for use in this embodiment of the present invention.

The bleaching detergent compositions of the present invention are substantially free of water soluble silicate compounds and comprise two essential components: (a) a bleaching agent; and (b) a detergent surface active agent.

The bleaching agent useful in such compositions comprises a peroxygen compound in combination with an activator therefor. The useful peroxygen compounds include compounds that release hydrogen peroxide in aqueous media, such as, alkali metal perborates, e.g., sodium perborate and potassium perborate, alkali metal perphosphates and alkali metal percarbonates.

The alkali metal perborates are usually preferred because of their commercial availability and relatively low cost.

Conventional activators such as those disclosed, for example, at column 4 of U.S. Patent 4,259,200 are suitable for use in conjunction with the aforementioned peroxygen compounds, such disclosure being incorporated herein by reference. The polyacylated amines are generally of special interest, tetraacetyl ethylene diamine (TAED) in particular being a highly preferred activator. The TAED is preferably present in the compositions of the present invention in the form of "coated" granules which contain the TAED and a suitable carrier material such as a mixture of sodium and potassium triphosphate. Such coated TAED granules are conveniently prepared by mixing finely divided particles of sodium triphosphate and TAED and then spraying onto such mixture an aqueous solution of potassium triphosphate using suitable granulation equipment such as a rotating pan granulatpr.A typical method of preparation for this type of coated TAED granules is described in U.S. Patent 4,283,302 to Foret, et al. The granules of TAED have a preferred particle size distribution as follows: 0-20% greater than 1 50 micrometres; 10-100% greater than 100 micrometres but less than 150 micrometres; 0-50% less than 75 micrometres; and 0-20% less than 50 micrometres. Another particularly preferred particle size distribution is where the median particle size of TAED is 1 60 micrometers, i.e. 50% by weight of the particles have a size greater than 1 60 micrometers. The aforementioned size distributions refer to the TAED present in the coated granules, and not to the coated granules themselves.The molar ratio of peroxygen compound to activator can vary widely depending upon the particular choice of peroxygen compound and activator. However, molar ratios of from about 0.5:1 to about 25:1 are generally for providing satisfactory bleaching performance.

The bleaching agent may optionally also contain a peroxyacid compound in combination with the peroxygen compound and activator. Useful peroxyacid compounds include water-soluble peroxyacids and their water-soluble salts. The peroxyacids can be characterized by the following general formula:

wherein R represents an alkylene group containing from 1 to about 20 carbon atoms, or a phenylene group, and Z represents one or more of a hydrogen atom or a halogen atom or an alkyl, aryl or anionic group.

The organic peroxyacids and the salts thereof can contain from about 1 to about 4, preferably 1 or 2, peroxygroups and can be aliphatic or aromatic. The preferred aliphatic peroxyacids include diperoxyazelaic acid, diperoxydodecanedioic acid and monoperoxysuccinic acid. Among the aromatic peroxyacid compounds useful herein, monoperoxyphthalic acid (MPPA), particularly the magnesium salt thereof, and diperoxyterephthalic acid are especially preferred. A detailed description of the production of MPPA and its magnesium salt is set forth on pages 7-10, inclusive, of European Patent Publication 0,027,693, published April 29 1981, the aforementioned pages 7-10 being incorporated herein by reference.

The bleaching detergent compositions of the present invention are characterized by being substantially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which are essentially comprised of a mixture of three components: an organic activator for the peroxygen compound; a water-insoluble silicate compound, such as clay or zeolite; and a non ionic surfactant, such mixture being at least 80%, by weight of the agglomerate particles. The agglomerate particles which are precluded from use herein are of the type formed in equipment such as a pan granulator and serve to incorporate the bleach activator in a matrix of materials as described in European Patent Publication No. 0,028,432.In one particular embodiment of the present invention, the bleaching compositions are further characterized by being substantially free of sequestering agents having a stability constant for Cu2+ complex formation above about 20 in water at 25"C and at an ionic strength of 0.1 mole/litre.

The water-insoluble silicate materials which may be advantageiously employed in the present bleaching compositions are preferably aluminosilicates such as zeolites and smectite-type clays.

The crystalline types of zeolite which may be employed include those described in "Zeolite Molecular Seives" by Donald W. Breck, published in 1 974 by John Wiley s Sons, typical commercially available zeolites being listed in Table 9.6 at pages 747-749 of the test, such Table being incorporated herein by reference. Zeolite structures of type A are especially desirable and are extensively described in the art; see, for example, page 1 33 of the aforementioned Breck Text as well as U.S. Patent No. 2,882,243. The zeolites are particularly useful as builder salts in heavy duty detergent compositions.

The aforementioned smectite-type clays are three-layer clays characterized by the ability of the layered structure to increase its volume several-fold by swelling or expanding when in the presence of water to form a thixotropic gelatinous substance. There are two classes of smectitetype clays: in the first class, aluminium oxide is present in the silicate crystal lattice; in the second class, magnesium oxide is present in the silicate crystal lattice. Atom substitution by iron, magnesium, sodium, potassium, calcium and the like can occur within the crystal lattice of the smectite clays. It is customary to distinguish between clays on the basis of their predominant cation. For example, a sodium clay is one in which the cation is predominantly sodium.With regard to the bleaching detergent compositions of the present invention, aluminium silicates wherein sodium is the predominant cation are preferred, such as, for example, bentonite clays.

Among the bentonite clays, those from Wyoming (generally referred to as western or Wyoming bentonite) are especially preferred. Calcium and magnesium clays are also useful albeit less preferred for purposes of the present invention.

Preferred swelling bentonites are sold under the trademark Mineral Colloid, as industrial bentonites, by Benton Clay Company, an affiliate of Georgia Kaolin Co. These materials which are the same as those formerly sold under the trademark THIXO-JEL, are selectively mined and beneficiated bentonites, and those considered to be most useful are available as Mineral Colloid No's. 101, etc. corresponding to THIXO-JELs No's. 1, 2, 3 and 4. Such materials have pH's (6% concentration in water) in the range of 8 to 9.4, maximum free moisture contents of about 8% and specific gravities of about 2.6, and for the pulverized grade at least about 85% (and preferably 100%) passes through a 200 mesh U.S. sieve Series sieve (which has openings 74 micrometres across) and most preferably all the particles pass through such a sieve.The swelling capacity of the bentonite in water is usually in the range of 3 to 1 5 ml/gram, and its viscosity, at a 6% concentration in water, is usually from about 8 to 30 centipoises.

In a particular preferred embodiment of the present invention, the carrier particles comprise agglomerates of finely divided bentonite, of particle sizes less than No. 200 Sieve U.S. Sieve Series (which have openings 74 micrometres across) agglomerated to particles of sizes essentially in the No's 10-100 sieve range U.S. Series (which have openings 2000 to 149 micrometres across) of a bulk density in the range of 0.7 to 0.9 g/ml and a moisture content of 8 to 13%. Such agglomerates include about 1 to 15% of a binder or agglomerating agent to assist in maintaining the integrity of the agglomerates until they are added to water, in which it is intended that they disintegrate and disperse. A detailed description of the method of preparation of such agglomerates is set forth in U.S. Serial No. 366,587 on which is based our co-pending G.B.Application No. 8309605 which is iricorporated herein by reference.

Instead of utilizing the THIXO-JEL or Mineral Colloid bentonites one may also employ equivalent competitive products, such as that sold by American Colloid Company, Industrial Division, as General Purpose Bentonite Powder, 325 mesh, which has a minimum of 95% thereof finer than 325 mesh or 44 microns in diameter (wet particle size) and a minimum of 96% finer than 200 mesh or 74 microns diameter (dry particle size). Such a hydrous aluminium silicate consists principally of montmorillonite (90% minimum), with smaller proportions of feldspar, biotite and selenite.A typical analysis, on an ''anhydrous" basis, is 63.0% silica, 21.5% alumina, 3.3% of ferric ions (as Fe203), 0.4% of ferrous iron (as FeO), 2.7% of magnesium (as MgO), 2.6% of sodium and potassium (as Na20), 0.7% of calcium, (as CaO), 5.6% of crystal water (as H20) and 0.7% of trace elements.

Although the western bentonites are preferred it is also possible to utilize synthetic bentonites, such as those which may be made by treating Italian or similar bentonites containing relataively small proportions of exchangeable monovalent metals (sodium and potassium) with alkaline materials, such as sodium carbonate, to increase the cation exchange capacities of such products. It is considered tha the Na20 content of the bentonite should be at least about 0.5%, preferably at least 1 % and more preferably at least 2% so that the clay will be satisfactorily swelling, with good softening and dispersing properties in aqueous suspension. Preferred swelling bentonites of the synthetic types described are sold under the trade names Laviosa and Winkelmann, e.g. Laviosa AGB and Winkelmann G-13.

The compositions of the present invention contain one or more surface active agents comprising an anionic, nonionic, cationic, ampholytic or zwitterionic detergent or mixtures thereof.

Among the anionic surface active agents useful in the present invention are those surface active compounds which contain an organic hydrophobic group containing from about 8 to 26 carbon atoms and preferably from about 10 to 18 carbon atoms in their molecular structure and at least one water-solubilizing sulphonate, sulphate, carboxylate, phosphonate or phosphate group 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 alkanol-ammonium salts) of higher fatty acids or resin salts containing from about 8 to 20 carbon atoms and preferably 10 to 1 8 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 sulphated and sulphonated detergents having an alkyl radical containing from about 8 to 26, and preferably from about 1 2 to 22 carbon atoms. (The term "alkyl" includes the alkyl portion of the higher acyl radicals).

Examples of the sulphonated anionic detergents are the higher alkyl mononuclear aromatic sulphonates such as the higher alkyl benzene sulphonates containing from about 10 to 1 6 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 sulphonates, higher alkyl toluene sulphonates and higher alkyl phenol sulphonates.

Other suitable anionic detergents are the olefin sulphonates including long chain alkene sulphonates, long chain hydroxyalkane sulphonates or mixtures of alkene sulphonates and hydroxyalkane sulphonates. The olefin sulphonate detergents may be prepared in a conventional manner by the reaction of sulphur trioxide, SO3, 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 = CHR' wherein R represents a higher alkyl group of from about 6 to 23 carbons and R' represents an alkyl group containing from about 1 to 1 7 carbon atoms, or a hydrogen atom to form a mixture of sultones and alkene suiphonic acids which is then treated to convert the sultones to sulphonates.Other examples of sulphate or sulphonate detergents are paraffin sulphonates containing from about 10 to 20 carbon atoms, and preferably from about 1 5 to 20 carbon atoms. The primary paraffin sulphonates are made by reacting long chain alpha olefins and bisulphites. Paraffin sulphonates having the sulphonate group discributed along the paraffin chain are shown in U.S. No. 2,503,280; 2,507,088; 3,260,741: 3,372,188 and German Patent No. 735,096.

Other suitable anionic detergents are sulphated ethoxylated higher fatty alcohols of the formula RO(C2H4O)rnSO3M, wherein R represents a fatty alkyl group of from 10 to 1 8 carbon atoms, m is from 2 to 6 (preferably having a value from 1/5 to 1/2 the number of carbon atoms in the R group and M represents a solubilizing salt-forming cation, such as an alkali metal, ammonium, lower alkylamino or lower alkanolamino, or a higher alkyl benzene sulphonate wherein the higher group is of 10 to 1 5 carbon atoms. The proportion of ethylene oxide in the polyethoxylated higher alkanol is of 11 to 1 5 carbon atoms.To maintain the desired hydrophile-lipophile balance, when the carbon atom content of the alkyl chain is in the lower portion of the 10 to 1 8 carbon atom range, the ethylene oxide content of the detergent may be reduced to about two moles per mole whereas when the higher alkanol is of 1 6 to 18 carbon atoms in the higher part of the range, the number of ethylene oxide groups may be increased to 4 or 5 and in some cases to as high as 8 or 9. Similarly, the salf-forming cation may be altered to obtain the best solubility. It may be any suitably solubilizing metal or radical but will most frequently be an alkali metal, e.g. sodium, or ammonium.If lower alkylamine or alkanolamine groups are utilized the alkyls and alkanols will usually contain from 1 to 4 carbon atoms and the amines and alkanolamines may be mono-, di- or tri-substituted, as in monoethanolamine, diisopropanolamine and trimethylamine. A preferred polyethoxylated alcohol sulphate detergent is available from Shell Chemical Company and is marketed as Neodol (Registered Trade Mark) 25-3S.

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 sulphonates (LABS), and especially those wherein the alkyl group is a straight chain alkyl radical of 1 2 or 1 3 carbon atoms.

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 aliphatic or alkyl aromatic hydrophobic compound with ethylene oxide (hydrophilic in nature). Practically any hydrophobic compound having a carboxy, hydroxy, amido or amino 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 detergent employed is preferably a poly-lower alkoxylated higher alkanol wherein the alkanol is of 10 to 1 8 carbon atoms and wherein the number of moles of lower alkylene oxide (of 2 or 3 carbon atoms) is from 3 to 1 2. Of such materials it is preferred to employ those wherein the higher alkanol is a higher fatty alcohol of 11 to 1 5 carbon atoms and and which contain from 5 to 9 lower alkoxy groups per mole. Preferably, the lower alkoxy group is ethoxy but in some instances, it may be desirably mixed with propoxy, the latter, it present, usually being a minor (less that 50%) constituent. Exemplary of such compounds are those wherein the alkanol is of 1 2 to 1 5 carbon atoms and which contain about 7 ethylene oxide groups per mole, e.g.Neodol (Registered Trade Mark) 25-7 and Neodol 23-6.5, which products are made by Shell Chemical Company, Inc. The former is a condensation product of a mixture of higher fatty alcohols averaging about 1 2 to 1 5 carbon atoms, with about 7 moles of ethylene oxide and the latter is a corresponding mixture wherein the carbon atom content of the higher fatty alcohol is 12 to 13 and the number of ethylene oxide groups per mole averages about 6.5. The higher alcohols are primary alkanols. Other examples of such detergents include Tergitol (Registered Trade Mark) 15-S-7 and Tergitol 15-S-9, both of which are linear secondary school ethoxylates made by Union Carbide Corporation.The former is a mixed ethoxylation product of an 11 to 1 5 carbon atom linear secondary alkanol with seven moles of ethylene oxide and the latter is a similar product but with nine moles of ethylene oxide being reacted.

Also useful in the compositions of the present invention are the higher molecular weight nonionics, such as Neodol 45-11, which are similar ethylene oxide condensation products of higher fatty alcohols, the higher fatty alcohol being of 14 to 1 5 carbon atoms and the number of ethylene oxide groups per mole being about 11. Such products are also made by Shell Chemical Company.

Zwitterionic detergents such as the betaines and sulphobetaines having the following formula are also useful:

wherein R represents an alkyl group containing from about 8 to 18 carbon atoms, R2 and R3 each represent an alkyl or hydroxyalkyl group containing about 1 to 4 carbon atoms, R4 represents an alkylene or hydroxyalkylene group containing 1 to 4 carbon atoms, and X represents a carbon atom or an S:O group. The alkyl group can contain one or more intermediate linkages such as amido, ether, or polyether linkages of non-functional substituents such as hydroxyl or halogen which do not substantially affect the hydrophobic character of the group. When X represents a carbon atom, the detergent is called a betaine; and when X represents an S:O group, the detergent is called a sulphobetaine 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 RNH2 wherein R represents an alkyl group containing from about 1 2 to 1 5 atoms; diamines having the formula RNHC2H4NH2 wherein R represents an alkyl group containing from about 1 2 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 R1CONHC2H4NH2 wherein R' represents an alkyl group containing from about 8 to 20 carbon atoms, such as N-2aminoethyl-stearyl 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, or methosulphate. The alkyl group may contain intermediate linkages such as amide which do not substantially affect the hydrophobic character of the group, for example stearyl amido propyl quaternary ammonium chloride. Typical quaternary ammonium detergents are ethyl-di-methylstearyl-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 methosulphates and acetates.

Ampholytic detergents are also suitable for use is compositions according to the present invention. Ampholytic detergents are well known in the art and many operable detergents of this class are disclosed by Schwartz, Perry and Berch in the aforementioned "Surface Active Agents and Detergents". Examples of suitable amphoteric detergents include: alkyl beta-iminodipropionates, RN(C2H4COOM)2; alkyl beta-amino propionates, RN(H)C2H4 COOM; and long chain imidazole derivatives having the general formula:

wherein in each of the above formulae R represents an acyclic hydrophobic group containing from about 8 to 1 8 carbon atoms and M represents a cation to neutralize the charge of the anion.Specific operable amphoteric detergents include the disodium salt of undecylcycloimidinium-ethoxyethionic acid-2-ethionic acid, dodecyl beta alanine, and the inner salt of 2trimethylamino lauric acid.

The bleaching detergent compositions of the present 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, carbonates, and the like. Organic builders include water-soluble phosphonates, polyphosphonates, polyhydroxysulphonates, 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. Patent Nos. 3,213,030; 3,422,021; 3,422,137 and 3,400,176. Pentasodium tripolyphosphate and tetra sodium pyrophosphate are especially preferred water-soluble inorganic builders.

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

Water-soluble organic builders are also useful. For example, the alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxysulphonates are useful builders for the compositions and processes of the present 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 and tetra-) acids, carboxymethoxysuccinic acid and citric acid.

Water insoluble builders may also be used, particularly the complex silicates and more particularly, the complex sodium alumino silicates such as, zeolites, e.g. zeolite 4A, a type of zeolite molecule wherein the univalent cation is sodium and the pore size is about 4 Angstroms.

The preparation of such type of zeolite is described in U.S. Patent 3,114,603. The zeolites may be amorphous or crystalline and have water of hydration as known in the art.

An inert, water-soluble filler salt is desirably included in the laundering compositions of the present invention. A preferred filler salt is an alkali metal sulphate, such as potassium or sodium sulphate, the latter being especially preferred.

Various adjuvants may be included in the laundry detergent compositions of the present invention. In general, these include perfumes; colourants, e.g. pigments and dyes; bleaches, such as sodium perborate; antiredeposition agents, such as alkali metal salts of carboxymethylcellulose; optical brighteners, such as anionic, cationic or nonionic brighteners; foam stablizers, such as alkanolamides, and the like, all of which are well known in the fabric washing art for use in detergent compositions. Flow promoting agents, commonly referred to as flow aids, may also be employed to maintain the particulate compositions as free flowing beads or powder.

Starch derivatives and special clays are commercially available as additives which enhance the flowability of otherwise tacky or pasty particulate compositions, two of such clay additives being presently marketed under the tradenames "Satintone" and "Microsil".

A preferred bleaching detergent composition in accordance with the present invention typically comprises (a) from about 2 to 50%, by weight, of a bleaching agent comprising a peroxygen compound in combination with an activator therefor; (b) from about 5 to 50%, by weight, of a detergent surface active agent; (c) from about 1 to about 60% by weight, of a detergent builder salt; and (d) from about 0.1 to about 10%, by weight, of a sequestering agent; such composition being characterized by being substantially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise an activator for a peroxygen compound, a water-insoluble silicate compound and a non ionic surfactant.The balance of the composition will predominantly comprise water, filler salts, such as, sodium sulphate, and minor additives selected from among the various adjuvants described above.

The particulate bleaching detergent compositions of the present invention are prepared by admixing the bleaching agent and optional sequestering agent with the spray dried detergent composition, the latter being formulated so as to avoid the use of water-soluble silicate compounds, most notably, sodium silicate. The presence of very minor amounts of water-soluble silicate compounds in the final compositions, i.e. below about 0.5%, preferably below about 0.2%, and most preferably no greater than about 0.1 %, by weight, such as may occur with the use of silicate-containing pigments or dyes, or upon contact of the aqueous crutcher slurry with residual amounts of sodium silicate in the spray tower, is contemplated by the present invention.

The spray drying of a silicate-free detergent formulation may result in a relatively dusty granular product due to the absence of silicate as a binder for the spray dried beads. However, alternative organic binder materials may be employed, such as, for example, starch, carboxymethyl-cellulose and materials comparable thereto. The strength of the spray dried beads may also be enhanced by maximizing the solids content of the silicate-free slurry in the crutcher and/or by maintaining the inlet temperature of the hot air stream in the spray tower as low as possible.

The bleaching agent can be mixed either directly with the spray dried powder or the bleaching agent and optional sequestering agent can be separately or collectively coated with coating material to 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 sulphate, polyvinyl alcohol, lauric acid and its salts and the like.

The bleaching detergent compositions of the present invention are desirably added to the wash solution in an amount sufficient to provide from about 3 to about 1 00 parts of active oxygen per million parts of solution, a concentration of from about 5 to about 40 ppm being generally preferred.

The particulate bleaching detergent compositions described above may be produced by such methods as spray-drying, dry-blending, or agglomeration of the individual components.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying examples.

EXAMPLE 1 A preferred silicate-free bleaching detergent composition consists of the ingredients set out below in Table 1.

TABLE 1 Component Weight Percent Sodium linear Cro-Ca3 alkyl benzene 6 sulphonate Ethoxylated C"-C,8 primary alcohol 3 (11 moles EO per mole alcohol) Soap (sodium salt of C,2-C22 4 carboxylic acid) Pentasodium tripolyphosphate (TPP) 32.0 EDTA 0.5 TAED 2.3 Carboxymethyl cellulose 0.5 Sodium perborate tetrahydrate 1 3.2 Optical brighteners, pigment and 0.4 perfume Proteolytic enzymes 0.5 Sodium sulphate and water balance The foregoing product is produced by spray drying on aqueous slurry containing 60%, by weight, of a mixture containing all of the above components except the enzyme, perfume, TAED and sodium perborate. The resultant particulate spray dried product has a particle size in the range of 14 mesh to 270 mesh, (U.S. Sieve Series) (which have openings 1.41 mms to 53 microns across). The spray dried product is then mixed in a rotary drum with the appropriate amounts of sodium perborate of similar mesh size, TAED, enzyme and perfume to yield a particulate product having a moisture content of approximately 18%, by weight.

The above-described product is used to wash soiled fabrics by hand-washing as well as in an automatic washing machine, good laundering and bleaching performance being obtained for both methods of laundering.

Other satisfactory products can be obtained by varying the concentrations of the following principal components in the above-described composition as set out in Table 2 below.

TABLE 2 Component Weight Percent Alkyl benzene sulphonate 4-12 Ethoxylated alcohol 1-6 Soap 1-10 TPP 15-50 Enzymes 0.1-1 EDTA 0.1-2 TAED 1-10 Sodium perborate 5-20 For highly concentrated heavy duty detergent powder, the alkyl benzene sulphonate, TPP and the soap components in the above described composition may be omitted, and the ethoxylated alcohol content may be increased to an upper limit of 20%.

EXAMPLES 2A to 2F Bleaching tests are carried out as described below comparing the bleaching performance of water-soluble silicate-free bleaching detergent compositions in accordance with the present invention and corresponding silicate-containing compositions, the latter compositions being comparable to the former in nearly all respects except for the presence of a water-soluble silicate compound. Specifically, the silicate-free compositions are characterized by the presence of sodium metaborate; the silicate-containing compositions contain sodium silicate. The compositions are formulated by post-adding to a spray-dried particulate detergent composition, granules of sodium perborate tetrahydrate and tetra-acetyl ethylene diamine (TAED) to form the bleaching detergent compositions shown in Table 3 below.The numbers indicated in Table 3 represent the percentage of each component, by weight, in the composition.

Examples 2D to 2F are comparison examples.

TABLE 3 Component Composition Example 2A 2B 2C 2D 2E 2F Sodium linear C10-C13 8% 8% 8% 8% 8% 8% benzene sulphonate Ethoxylated C"-C,8 primary alcohol (11 moles EO per mole alcohol) 3 3 3 3 3 3 Soap (sodium salt of C12-C22 carboxylic acid) 3 3 3 3 3 3 Sodium silicate (1Na20:2Si02) - - 4 4 4 Sodium metaborate 5 5 5 - - Pentasodium tripoly phosphate (TPP) 35 35 35 35 35 35 Optical brightener (stilbene) 0.2 0.2 0.2 0.2 0.2 0.2 Sodium perborate tetra hydrate 6 6 6 6 6 6 TAED 5 5 5 5 5 5 EDTA - 1 - - 1 EDITEMPA1 - - 1 - - 1 Sodium sulphate 21 20 20 21 20 20 Water ---------------------------balance--------------------------- Note on Table 3 (1) Sold as Dequest 2041 by Monsanto Company, St. Louis, Missouri.

Bleaching tests are carried out in an Ahiba apparatus at maximum temperatures of 60"C and 90"C, respectively, as hereinafter described. 600 ml of tap water having a water hardness of about 320 ppm, as calcium carbonate, are introduced into each of six buckets of the Ahiba apparatus. Six cotton swatches (8 cm X 1 2 cm) soiled with immedial black are introduced into each bucket, the initial reflectance of each swatch being measured with a Gardner XL 20 reflectometer.

Six grams of each of the compositions of Examples 2A to 2F described in Table 3 are introduced separately into the six buckets of the Ahiba apparatus, a different composition being introduced into each bucket. The bleaching detergent compositions are thoroughly mixed in each bucket with a blender-type apparatus and the wash cycle thereafter initiated. The bath temperature, initially at 30"C, is allowed to rise by about 1" Centigrade per minute until the maximum test temperature (60 or 90"C) is reached, such maximum temperature being then maintained for about 1 5 minutes. The buckets are then removed and each swatch washed twice with cold water and dried.

The final reflectance of the swatches are measured and the difference (ARd) between the final and initial reflectance values is determined. An average value of ARd for the six swatches in each bucket is then calculated. The results of the bleaching tests are set forth below in Table 4, the values of ARd being provided as an average value for the particular composition and test indicated.

TABLE 4 #Rd (Average) Example 2A 2B 2C 2D 2E 2F Test temperature Silicate-Free Compositions Silicte-Containing Composition Without Without Sequestrant 1% EDTA 1% EDITEMPA Sequestrant 1% EDTA 1% EDITEMPA 60 C 9.1 9.1 8.8 8.0 6.7 7.5 90 C 18.0 17.9 17.0 14.6 14.8 17.6 As indicated in Table 4, the silicate-free compositions of Examples 2A, 28 and 2C provide an improved bleaching performance relative to the silicate-containing compositions of Examples 2D to 2F at both test temperatures.Among the silicate-containing compositions, the one which contains 1% EDITEMPA, Example 2F, provides an improved bleaching effect relative to the composition of Example 2D which contains no sequestrant, but only at the higher test temperature of 90"C. However, at both test temperatures, the silicate-free composition of Example 2A containing no sequestrant provides the best bleaching effect of all compositions tested.

EXAMPLE 3 The active oxygen concentration in solution is determined as a function of time for separate wash solutions containing each of the compositions of Examples 2A to 2F described in Table 3.

The test procedure is as follows: On litre of tap water is introduced into a two litre beaker and then heated to a constant temperature of 60"C in a water bath. Ten grams of the particular composition being tested are added to the beaker (time = 0) with thorough mixing to form a uniform wash solution. After given periods of time (5, 15, 30, 45 and 60 minutes), a 50 ml aliquot is withdrawn from the wash solution and the total active oxygen concentration is determined by the procedure set forth below.

The aforementioned 50 ml aliquot is poured into a 300 ml Erlenmeyer flask fitted with a ground stopper and containing 1 5 ml of a sulphuric/molybdate mixture, the latter mixture having been prepared in large-scale amounts by dissolving 0.18 grams of ammonium molybdate in 750 ml of deionized water and then adding thereto 320 ml of H2S04 (about 36N) with stirring. The solution in the Erlenmeyer flask is thoroughly mixed and 5 ml of a 10% potassium iodide (Kl) solution in deionized water is then added thereto. The Erlenmeyer flask is sealed with a stopper, agitated and then allowed to stand in a dark place for seven minutes. The solution in the flask is then titrated with a solution of 0.1 N sodium thiosulphate in deionized water. The volume of thiosulphate required, in ml, is equal to the total active oxygen concentration, in millimole/litre, in the wash solution. The test results for the six compositions tested are shown in Table 5 below.

TABLE 5 Total Active Oxygen in Washing Solution (mmol/litre) Example 2A 2B 2C 2D 2E 2F Time (min.) Silicate-Free Compositions Silicate-Containing Compositions Without Without Sequestrant 1% EDTA 1% EDITEMPA Sequestrant 1% ECTA 1% EDITEMPA 5 3.3 3.5 3.2 2.1 2.1 3.2 15 3.0 3.3 3.1 1.4 1.4 2.3 30 2.4 3.0 2.6 0.8 0.8 2.0 45 1.8 2.8 2.2 0.4 0.5 1.3 60 1.4 2.7 2.0 0.2 0.3 3.1 As shown in Table 5, the silicate-free compositions of Examples 2A to 2C are substantially more stable and are characterized by a far slower loss of active oxygen from solution than the corresponding silicate-containing compositions of Examples 2D to 2F respectively.Among the silicate-containing compositions, the one containing 1 % EDITEMPA, Example 2F, provides the maximum stability, however, such composition is less stable than all of the silicate-free compositions, including the composition of Example 2A which contains no sequestrant. Among the silicate-free compositions, the presence of a sequestrant in the compositions of Examples 28 and 2C results in improved oxygen stability relative to the composition of Example 2A.

EXAMPLE 4 Bleaching tests are carried out in an Ahiba apparatus as indicated below comparing the bleaching performance of a bleaching detergent composition free of water-soluble silicates in accordance with the invention, Example 48, and a water-soluble silicate-containing composition, Example 4A, which is a comparison example. As indicated below, the two compositions are comparable in nearly all respects except for the presence of sodium silicate in the composition of Example 4A. A crystalline zeolite material is present in both compositions. The compositions are formulated by post-adding to a particulate detergent composition formed from an aqueous slurry which is dried on a steam drum layer (an operation equivalent to spray drying), particles of sodium perborate tetrahydrate and tetraacetyl ethylene diamine (TAED) to form the bleaching detergent composition shown in Table 6 below.The numbers indicated in Table 6 represent the percentage of each component, by weight, in the composition.

TABLE 6 Component Composition Example 4A 4B (Silicate- (Silicate containing free) Sodium linear C,O-Cl3 alkyl 6 6 alkyl benzene sulphonate Ethoxylated C,1-C,8 primary 3 3 alcohol (11 moles EO per mole alcohol) Soap (Sodium salt of C,2-C22 4 4 carboxylic acid) Sodium silicate (1 Na20:2SiO2) 4 Pentasodium tripolyphosphate 1 9 1 9 (TPP) Optical brightener (stilbene) 0.2 0.2 Zeolite 19 19 Sodium perborate tetrahydrate 13.3 13.3 TAED 2.3 2.3 Water 5 5 Sodium sulphate balance balance The bleaching test is carried out in accordance with the test procedure set forth in Example 2, and the results of such test are shown in Table 7 below. The values of ARd are provided as an average value for the test indicated.

TABLE 7 dRd (Average) Example 4A 4B Test Composition free Tempera- Composition containing of water-soluble ture water-soluble silicate silicate 60"C 5.0 6.1 95"C 13.2 14.9 As indicated in Table 7, the water-soluble silicate-free composition of Example 4B provides a significantly improved bleaching performance relative to the silicate-containing composition of Example 4A.

Claims (20)

1. A particulate bleaching detergent composition comprising: (a) a bleaching agent comprising a peroxygen compound in combination with an activator therefor; and (b) at least one anionic, cationic, nonionic, ampholytic or zwitterionic detergent or mixture thereof, the said bleaching detergent composition being substantially free of (i) -water-soiuble silicate compounds and (ii) agglomerate particles which essentially comprise a mixture of an activator for a peroxygen compound, a water-insoluble silicate compound and a nonionic surfactant.

2. A composition as claimed in Claim 1 also containing a sequestering agent.

3. A composition as claimed in Claim 2 in which the said sequestering agent comprises ethylene diamine tetraacetic acid or a water-soluble salt thereof or a mixture thereof.

4. A composition as claimed in Claim 2 in which the said sequestering agent comprises diethylene triamine pentamethylene phosphonic acid or a water-soluble salt thereof or a mixture thereof.

5. A composition as claimed in any one of Claims 1 to 4 which is substantially free of sequestering agents having a stability constant above about 20 for Cu2+ complex formation in water at 25"C and at an ionic strength of 0.1 mole/litre.

6. A bleaching detergent composition comprising: (a) from about 1 to about 50%, by weight, of a bleaching agent comprising a peroxygen compound in combination with an activator therefor; (b) from about 5 to about 50%, by weight, of an anionic, cationic, nonionic, ampholytic or zwitterionic detergents or a mixture thereof; (c) from about 1 to about 60%, by weight, of a detergent builder salt; (d) from about 0.1 to about 10%, by weight, of a sequestering agent; and (e) the balance comprising water and optionally a fillter salt; the said bleaching detergent composition being substantially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise a mixture of an activator for a peroxygen compound, a water-insoluble silicate compound and a nonionic surfactant.

7. A composition as claimed in any one of Claims 1 to 6 in which the said bleaching agent comprises an alkali metal perborate in combination with tetraacetyl ethylene diamine (TAED).

8. A composition as claimed in Claim 7 in which the said TAED is contained in granules in combination with a mixture of sodium and potassium triphosphate.

9. A composition as claimed in Claim 7 or Claim 8 in which the said TAED has the following particle size distribution: 0-20% greater than 1 50 micrometers; 10-100% greater than 100 micrometers but less than 1 50 micrometers; 0-50% less than 75 micrometers; and 0-20% less than 50 micrometers.

10. A composition as claimed in Claim 7, 8 or 9 in which about 50% of the particles of TAED have a size greater than 1 60 micrometers.

11. A composition as claimed in any one of Claims 1 to 10 in which at least 80%, by weight, of the said agglomerate particles consist of the said mixture of bleaching agent and detergent.

1 2. A composition as claimed in any one of Claims 1 to 11 also containing a detergent builder salt.

1 3. A composition as claimed in Claim 1 2 in which the said builder salt is a zeolite.

14. A composition as claimed in Claim 12 or Claim 1 3 in which the said builder salt comprises pentasodium tripolyphosphate.

1 5. A composition as claimed in any one of Claims 1 to 14 in which the said surface active agent is an anionic detergent.

1 6. A composition as claimed in Claim 1 5 in which the said anionic detergent is a linear alkyl benzene sulphonate.

1 7. A composition as claimed in any one of Claim 1 to 16 also containing a bentonite clay.

18. A composition as claimed in any one of Claims 1 to 1 7 in which the bleaching agent also contains a peroxyacid compound.

1 9. A composition as claimed in Claim 1 substantially as specifically described herein with reference to any one of Examples 1, 2A to 2C, or 4B.

20. A process for bleaching which comprises contacting the stained and/or soiled material to be bleached with an aqueous solution of a particulate bleaching detergent composition as claimed in any one of Claims 1 to 1 9.