EP0743976A1

EP0743976A1 - Hard surface cleaner containing oxidising composition

Info

Publication number: EP0743976A1
Application number: EP95907747A
Authority: EP
Inventors: Vincent Brian Croud; Stephen James Tompsett
Original assignee: Warwick International Group Ltd
Current assignee: Warwick International Group Ltd
Priority date: 1994-02-07
Filing date: 1995-02-07
Publication date: 1996-11-27
Also published as: AU1584395A; WO1995021236A1; GB9414625D0

Abstract

The use of N-acyl and O-acyl bleach activator compounds to generate peroxy acids in aqueous acidic environments. The product is used in situ as a hard surface cleaner. Compositions for forming the aqueous acidic peroxy acid products include surfactant, preferably non-ionic and amphoteric surfactants. The pH is preferably below 6.5.

Description

Hard surface cleaner containing oxidising composition

This invention relates to cleaning of hard surfaces, such as domestic, industrial and/or institutional surfaces. In the invention, an activator is used during a peroxide bleaching step carried out at a pH which is acidic, or slightly alkaline.

Both solid and liquid types of hard surface cleaners are known. Solid particulate hard surface cleaners may be used in their solid form and provide cleaning by abrasion, or may be dissolved in water before use. Liquid hard surface cleaners are also known.

Many hard surface cleaners are known which do not include an oxidising/bleaching agent and whilst these have been found to provide a degree of success, in particular for cleaning greasy stains, it has been found that the incorporation of a bleaching agent into such a hard surface cleaner gives substantially beneficial cleaning properties. The existing hard surface cleaners are generally alkaline compositions. Acidic lime-scale removing compositions are also known. However, they are highly acidic, and do not include bleach activator components and cannot be used for general cleaning purposes, without a post-rinsing step. W094/13776 describes aqueous acidic bleaching compositions which incorporate a surfactant suspending system, comprising sulphate or sulphonate and fatty acid. There are no disclosures of other mixed surfactants. EP-A-092932 discloses bleaching or disinfection emulsion compositions comprising aqueous acidic hydrogen peroxide solution with an organic phase comprising an end ester.

It would be desirable to find a system for hard surface cleaning having stability and the advantages of a bleach precursor/activator combination but where the precursor and activator and/or the subsequent cleaning (oxidisation or bleaching) step may be carried out under acidic conditions and may be carried out at relatively low concentrations so that for example, they can be used in no- rinse cleaning formulations.

In accordance with the present invention there is provided a process comprising obtaining an oxidising composition comprising a peroxygen source, an activator compound and at least 2% by weight (based on the total weight of composition) surfactant comprising nonionic and amphoteric surfactant, then reacting the peroxygen source with the activator compound which is an acyl donor in a first step in aqueous solution at a pH below pK_a (1) (where pK_a (1) is the pK_a of the percarboxylic acid corresponding to the acyl group of the activator) , to form an oxidising product which is a stronger oxidising agent than the peroxygen source and the product solution is subsequently used as a hard surface cleaner at a pH below pK_a (1) in a second, bleaching step.

The invention also comprises a solid composite hard surface cleaner product comprising a peroxygen source; a bleach activator, a surfactant and an acidifying optional component such that when the product contacts water it forms an acidifying component and surfactant. Preferably when the product contacts water it dissolves to form an acidic solution comprising peroxygen source, activator acidifying component and surfactant. However for solid applications such as scouring powders, full dissolution may not take place.

The surfactant preferably comprises a mixture of non¬ ionic and amphoteric surfactant.

The peroxygen source is reacted with the activator compound in a first step in solution, generally aqueous, at a pH below pK_a(l) . Preferably the reaction takes place at a pH below 7, or even below 6.5 or below pH 6. The pK_a of the percarboxylic acid corresponding to the acyl group of the activator may be for example up to pH 9 but is generally no greater than 8.5, or even 8.

The activator may be any one or mixtures of more than one acyl donor. Preferably, the activator is one or mixtures of more than one of the compounds of the formula I:

0

in which L is a leaving group attached via an oxygen or a nitrogen atom to the C=0 carbon atom and R is an alkyl, aralkyl, alkaryl, or aryl group, any of which groups has up to 24 carbon atoms and may be substituted or unsubstituted.

The leaving group L is preferably a compound, the conjugate acid of which has a pK_a in the range 4-13, preferably 7-11, most preferably 8-11.

It is preferred that R is an aliphatic group, preferably a C-_|.₁₈ alkyl group, or an aryl group.

In the present invention the term alkyl includes alkenyl and alkyl may be straight, branched or cyclic.

In the formula I, L and R may be joined to form a cyclic compound, usually a lactone or a lactam. These cyclic groups may include heteroatoms, for instance oxygen or optionally substituted nitrogen atoms, carboxyl groups as well as -CH₂- groups or substituted derivatives thereof.

They may be saturated or unsaturated. L can itself comprise a cyclic group, including heterocyclic groups, for instance joined to the C=0 group of the compound I via the heteroatom.

Substituents on R and L can include hydroxyl, =N-R in which R is selected from any of the groups represented by R and is preferably lower alkyl, amine, acyl, acyloxy, alkoxy, aryl, aroyl, aryloxy, aroyloxy, halogen, amido, and imido groups and the like as well as other groups not adversely affecting the activity of the compound.

When the activator is a N-acyl compound preferred compounds include those having at least two carbon atoms in the acyl group, especially compounds having the formula II:

O R²

R 4-CII-NI-R3 ^∑I in which R is an alkyl, alkenyl, aralkyl, alkaryl or aryl group, any of which groups has up to 24 carbon atoms and may be substituted or unsubstituted, and -NR R is a leaving group in which R and R are independently selected from H, C^^-alkyl, -alkenyl, -aralkyl, alkaryl or -aryl groups, and carbonyl-containing moieties having at least 2 carbon atoms in which the carbonyl group is joined to the nitrogen atom in the formula I, in which R and R can be joined together as a cyclic group and/or R can be joined to either R or R to form a cyclic group. Particularly preferred compounds of formula II are those in which R⁴ is an aliphatic group, preferably a C^^-alkyl, or -alkenyl group, or is an aryl group.

When the activator is an O-acyl compound preferred compounds include esters of C₂ or higher carboxylic acids in which in the first step in aqueous solution, the peroxyen source is present at a concentration of less than 10M in the reaction mixture. Particularly preferred are compounds of formula III: O

R COR5 III in which R is as described above a alkyl, alkenyl, aralkyl, alkaryl or aryl group, any of which groups has up to 24 carbon atoms and may be substituted or unsubstituted, and R⁵ is selected from C^-^-alkyl, -alkenyl, -aralkyl, - alkaryl and -aryl groups, any of which are substituted or unsubstituted, R 4 and R5 opti.onally bei.ng j.oi.ned to form a cyclic group. In the invention the compound of the formula I can be any N-acyl or O-acyl acyl-donor compound, which has been described as a bleach activator for use in laundry detergents. The compound of the formula I may be an anhydride, but is preferably an ester or, even more preferably, an amide derivative.

Amide derivatives include acyl imidazolides and N,N-di acylamides, such as TAED. Other examples of N-acyl derivatives are: a) 1, 5-diacetyl-2, 4-dioxohexahydro-l,3, 5-triazine (DADHT) ; b) N-alkyl-N-suphonyl carbonamides, for example the compounds N-methyl-N-mesyl acetamide, N-methyl-N-mesyl benzamide, N-methyl-N-mesyl-p-nitrobenzamide, andN-methyl- N-mesyl-p-methoxybenzamide; c) N-acylated cyclic hydrazides, acylated triazoles or urazoles, for example monoacetyl maleic acid hydrazide; d) θ,N,N-trisubstituted hydroxylamines, such as O-benzoyl- N,N-succinyl hydroxylamine, 0-p-nitrobenzoyl-N,N-succinyl hydroxylamine and 0,N,N-triacetyl hydroxylamine; e) N,N^,-diacyl sulphurylamides, for example N,N'-dimethy1- N,N'-dimethyl-N,N^,-diacetyl sulphury1 amide and N,N'- diethy1-N,N'-dipropionyl sulphurylamide; f) l,3-diacyl-4,5-diacyloxy-imidazolines, for example 1,3- diformyl-4,5-diacetoxy imidazoline, l,3-diacetyl-4,5- diacetoxy imidazoline, l,3-diacetyl-4,5-dipropionyloxy imidazoline; g) Acylated glycolurils, such as tetraacetyl glycoluril and tetraproprionyl glycoluril; h) Diacylated 2,5-diketopiperazines, such as 1,4-diacetyl- 2,5-diketopiperazine, 1,4-dipropionyl-2,5-diketopiperazine and 1,4-dipropionyl-3,6-dimethyl-2,5-diketopiperazine; i) Acylation products of propylene diurea and 2,2-dimethyl propylene diurea, especially the tetraacetyl or tetrapropionyl propylene diurea and their dimethyl derivatives; j) Alpha-acyloxy-(N,N^,)polyacyl malonamides, such as alpha-acetoxy-(N,N') -diacetyl malonamide. k) 0,N,N-trisubstituted alkanolamines, such as 0,N,N- triacetyl ethanola ine. k') Cyanamides, such as those disclosed in DE-A-3 , 304,848. 1) N-acyl lactams, such as N-benzoyl-caprolactam, N-acetyl caprolactam, the analogous compounds formed from C₄.₁₀ lactams. m) N-acyl and N-alkyl derivatives of substituted or unsubstituted succinimide, phthalimide and of imides of other dibasic carboxylic acids, having 5 or more carbon atoms in the imide ring.

Alternatively the compound may be an ester, for instance n) sugar esters, such as pentaacetylglucose, o) esters of imidic acids such as ethyl benzimidate, p) triacylcyanurates, such as triacetylcyanurate and tribenzoylcyanurate, q) esters giving relatively surface active oxidising products for instance of C₈.₁₈-alkanoic or -aralkanoic acids such as described in GB-A-864798, GB-A-1147871 and the esters described in EP-A-98129 and EP-A-106634, for instance compounds of the formula I where L comprises an aryl group having a sulphonic acid group (optionally salified) substituted in the ring to confer water solubility on a benzyl group, especially nonanoyloxy- benzenesulphonate sodium salt (NOBS) , isononanoyloxy- benzenesulphonate sodium salt (ISONOBS) and benzoyloxy- benzenesulphonate sodium salt (BOBS) r) phenyl esters of C_H.₂₂-alkanoic or -alkenoic acids, s) esters of hydroxylamine, t) geminal diesters of lower alkanoic acids and gem-diols, such as those described in EP-A-0125781 especially 1,1,5- triacetoxypent-4-ene and 1,1,5,5-tetraacetoxypentane and the corresponding butene and butane compounds, ethylidene benzoate acetate and bis(ethylidene acetate) adipate and u) enol esters, for instance as described in EP-A-0140648 and EP-A-0092932.

Where the activator is an anhydride it is preferably a solid material, and is preferably an intra-molecular anhydride, or a polyacid polyanhydride. Such anhydride compounds are more storage stable than liquid anhydrides, such as acetic anhydride. Anhydride derivatives which may be used as activator include v) intramolecular anhydrides of dibasic carboxylic acids, for instance succinic, aleic, adipic, phthalic or 5- norbornene-2,3-dicarboxylic anhydride. w) intermolecular anhydrides, including mixed anhydrides, of mono- poly-basic carboxylic acids, such as diacetic anhydride of isophthalic or perphthalic acid x) isatoic anhydride or related compounds such as described in WO-A-8907640 having the generic formula II

wherein Q is a divalent organic group such that Q and N together with the carbonyl groups and oxygen atom of the anhydride group form one or more cyclic structures and R is H, alkyl, aryl, halogen or a carbonyl group of a carboxyl containing function; or benzoxazin-4-ones as described in WO-A-8907639, that is compounds of the formula III

wherein 0/ is selected from the same groups as Q and R is H, alkyl, aryl, alkaryl, aralkyl, alkoxyl, haloalkyl, amino, aminoalkyl, carboxylic group or a carbonyl- containing function; preferably 2-methyl-(4H)3,1- benzoxazin-4-one (2MB4) or 2-phenyl-(4H) 3,l-benzoxazin-4- one (2PB4) ; y) polymeric anhydrides such as poly(adipic) anhydride or other compounds described in our co-pending application W0- A-9306203.

The peroxygen source may be hydrogen peroxide itself, but is preferably an inorganic persalt, for instance a percarbonate or, a perborate, for instance sodium perborate, or an organic peroxide such as benzoyl peroxide or urea peroxide. Mixtures of any of these peroxygen sources may also be used.

In the perhydrolysis reaction the amount of water present is preferably at least as much (in terms of moles) as the peroxygen source. Where the peroxygen source is hydrogen peroxide itself, the concentration of hydrogen peroxide is preferably less than 70% weight/volume (that is weight of hydrogen peroxide based on volume of water plus hydrogen peroxide plus other components in the mixture concerted) . Preferably the concentration is less than 60% weight by volume and more preferably less than 30% w/v. Where the product of the reaction is to be used in a domestic environment or other environment where it is difficult to take special precautions in handling the products, it is preferred for the concentration to be less than 15% or even 10% w/v or less than 5% w/v. The concentration is usually at least 0.2%, preferably at least 1% w/v, more preferably at least 2% w/v. Where the peroxygen source is other than hydrogen peroxide then the concentration is preferably such as to give the equivalent available oxygen as the quoted concentrations of hydrogen peroxide. The concentration of peroxygen source in the aqueous liquid is for instance less than 20M or even less than 10M, preferably less than 5M or sometimes even less than 3M down to 0.01M. Preferably the concentration is at least 0.05M, more preferably 0.1M, even more preferably at least 0.2M.

The pH in the bleaching step is usually less than 8.0, preferably less than 7.0, or even less than 6.0. The pH is usually more than 2.0, for instance more than 3.0, most preferably more than 5.0.

In the perhydrolysis step of the reaction the temperature is preferably in the range 0 to 95°C, more preferably in the range 10 to 80°C. The invention is most useful when the temperature is less than 60°C, or even less than 50°C, for instance less than 40°C or even around room temperature. The temperature is often above 20°C. The temperature in any subsequent bleaching step.is likely to be somewhat lower than the temperature in the first step, due to cooling on application. Preferred temperatures for the second, bleaching step are preferably in the same ranges as the temperature during the perhydrolysis step and is preferably substantially the same temperature especially where the product solution is immediately used for instance as a bleach or disinfectant. A particular advantage of using activators for the peroxygen source is that the oxidising product tends to be formed at a relatively low temperature, for instance at temperatures around ambient and less than hand hot which is advantageous from a safety point of view.

The present invention provides also an oxidising composition, and a new use of an oxidising composition comprising starting materials for the perhydrolysis reaction. Preferably the oxidising composition can simply be added to water to provide the entire reaction mixture. The hard surface cleaner oxidising composition therefore comprises a peroxygen source, an activator compound, at least 2% by weight surfactant (based on the total weight of the composition) as well, if necessary, as components for rendering the pH of an aqueous solution to which the components of the product are added below pK_a (1) (as defined above), generally below pH 7. Acidifying components may not be necessary where the peroxygen source itself is sufficiently acidic to achieve the desired pH.

In one preferred embodiment of the oxidising composition the activator is TAED. The peroxygen source may be hydrogen peroxide or a solid peroxygen compound.

In another preferred embodiment of the oxidising composition, the activator is any other activator which is solid at ambient temperatures.

In another preferred embodiment of the oxidising composition the peroxygen source is a solid, preferably an inorganic persalt.

An acidifying component may comprise an acid and/or buffering material. The component may comprise a polybasic organic acid, such as a polybasic carboxylic acid such as citric, succinic, or adipic acid or sulphamic acid. Citric acid is particularly preferred because it also acts as a builder for the product and may also aid in scale-removal. Alternatively the component may react with a by-product of the perhydrolysis reaction to increase the acidity in use. Where perborate is used, borate is a by-product and so any component known to react with borate to drop the pH, eg cis-l,2-diols, such as glycols and polyols, boric acid, or sodium dihydrogen phosphate can be used. Such acidifying components are also suitable for use where percarbonate is the peroxygen source.

Although the oxidising composition for the use of the present invention may contain the individual components each in separate compositions, for instance one of which contains the peroxygen source, another of which contains the activator and others of which contains each of the surfactant and an acidifying component, it is preferred to provide at least the activator, surfactant and acidifying component as a mixture in a single composition in a form in which they are stable. Such a composition which does not contain peroxygen source, may, for instance, be added to an aqueous solution of peroxgyen source such as aqueous hydrogen peroxide, which is readily commercially available, in the form of, for instance 60%, 20%, 10% or, preferably, 5% w/v or less solution. It is most preferred that the peroxygen source, acidifying component and activator or even all of the components to be provided in a single composition, in which the components do not react, and which is preferably therefore substantially water free.

The compositions may be in liquid form, for instance in a non-aqueous liquid medium, in which the components may be dissolved or dispersed. For instance particles of activator with protective coatings, for instance produced by microencapsulation techniques or spray coating of solid activator, may be suspended in an aqueous, or non aqueous, solution of peroxygen source. As an alternative to a solution of peroxygen source that component may also be suspended in the liquid medium, either in a separate liquid phase or in particulate dispersed phase, particles of solid peroxygen source optionally being coated with a protective coating. Coated particles of either peroxygen source or activator may be disrupted or diluted in to water or with abrasion. In the liquid compositions, the surfactant provides a mixture of surfactants comprising non-ionic and amphoteric surfactants.

Preferably the oxidising composition is in a solid form, for instance as a mixture of particles of the individual components or, more preferably, comprising particles each of which comprise all of the components. Such particles may be provided by techniques similar to those used in the laundry detergent industry, for instance including particles produced by spray drying liquid slurries, by granulation techniques using binders (for instance synthetic or natural polymers or derivatives) or by melt blending followed by extrusion or other techniques. In particular the solid compositions preferably include acidifying component.

Preferably the product contains the active ingredients in appropriate relative quantities so that when the composition is diluted (or the compositions are mixed) with water the first step of the reaction proceeds at the optimal rate and at the desired pH. The activator and peroxygen source are for instance present in relative amounts such that up to 500%, preferably 5% to 150% of the stoichiometric amount of activator (for complete reaction with the peroxygen source) is provided. Preferably the amount of activator is 10 to 100%, more preferably 20 to 80% of the stoichiometric amount.

The product solution comprises a surfactant. Any conventional surfactant may be used, selected from non¬ ionic, anionic, cationic, and amphoteric surfactants. At low pH anionic surfactants may have poor detergency properties. Substantial content of nonionic and/or amphoteric surfactants will increase the performance at acid pH. The surfactant may be incorporated in amounts of from 2% by weight of the composition (either solid or liquid) up to 40%. Preferably there will be no greater than 35% and most preferably no greater than 30% by weight surfactant. Preferably the surfactant will be added in amounts of at least 5% by weight of the composition. 1B surfactant mixture will generally comprise 40% or more by weight of the total weight of surfactant of a nonionic surfactant and may further comprise 1-60% by weight amphoteric surfactant.

Suitable nonionic surfactants include for example alkanolamides (such as CIO to C20) and/or ethoxylated alcohols, alkyl phenol ethoxylates, alkyl polyglucosides, glyceryl esters, sorbitan esters, phosphate esters etc. Preferred nonionic surfactants are coconut diethanolamide and alkylpolyglucosides. Although lauryl ether sulphate is generally considered to be anionic, it does have partial nonionic character which renders it relatively pH and hardness dependent.

Suitable amphoteric surfactants include for example betaines, such as alkyl betaines especially cocoamidopropyl betaine, sulphobetaines, and also imidazoline derivatives. Suitable cationic surfactants include for example quaternary ammonium salts, imidizolines and quaternised imidizolines.

Suitable anionic surfactants include any surfactant useful in a detergent for example salts of sulphonic or monoesterified sulphuric acids such as alkyl benzene sulphonate, alkyl sulphates, alkyl ether sulphates, olefin sulphonates, alkyl phenol sulphates, alkyl phenol ether sulphates, alkyl ethanolamine sulphate, alkyl ethanolamine ether sulphates, alpha sulpho fatty acids or esters, each having at least one alkyl or alkenyl group from 8 to 22, more usually 10 to 20 aliphatic carbon atom and the alkyl or alkenyl groups preferably being straight chain primary groups. Other suitable anionic surfactants include fatty alkyl sulphosuccinates, fatty alkyl ether sulphosuccinates, acyl sarcosinates, acyl taurides, and paraffin sulphonates. The preferred anionic surfactants are salts of alkali metals or alkaline earth metals, preferably sodium. Other salts include ammonium, monoethanolamine, diethanola ine, triethanolamine and alkyl amines having up to 7 aliphatic carbon atoms. Particularly preferred examples of anionic surfactants for use in the present invention include sodium dodecylbenzene sulphonate, potassium hexadecylbenzene sulphonate, sodium dodecyldimethylbenzyl sulphonate, sodium lauryl sulphate, ammonium lauryl monoethoxysulphate, monoethanolamine cetyl ethoxylate sulphate and paraffin sulphonates. Preferably the oxidising composition comprises at least 5% by weight surfactant, most preferably at least 7% by weight surfactant or even at least 10% by weight of the oxidising composition.

The compositions of the present invention preferably also include a chelating agent for calcium and/or magnesium, preferably at least for calcium. Where included there will generally be at least 0.1%, preferably at least 1%, and generally no greater than 10% and preferably no greater than 5% by weight chelating agent. One or mixtures of more than one chelating agent can be used. Particularly preferred chelating agents are EDTA, DTPA and phosphonates. Phosphonates are particularly preferred. The incorporation of a chelating agent is not only advantageous because improved peroxide stability of the oxidising composition results, but in addition give a further beneficial effect in that they provide limescale removing properties to the compositions.

The oxidising composition may include other additives, for instance stabilisers which stabilise the product before use, as well as stabilisers for the peroxy acid oxidising species formed in the reaction, such as any heavy metal sequestrant. In addition to the surfactants mentioned above, inorganic salts, for instance which affect the physical properties of the solid form or act as diluent may also be incorporated. Other ingredients may be included depending upon the mode of use of the composition on the final application of the reaction product, for instance perfumes, or agents to assist dissolution or dispersion of the product into water.

A preferred embodiment of the oxidising compositions for use in the present invention comprises a peroxygen source, an activator compound, at least 5% by weight surfactant and if necessary, an acidifying component.

The hard surface cleaner compositions of the present invention may be provided in a form which is suitable to be diluted directly into water to allow the first and second steps of the reaction to proceed without further additions. The hard surface cleaners of the invention include scouring-type cleaners, general purpose liquid cleaners and foam or mousse-type cleaners. All of these types of cleaners can be used in any application where disinfecting and/or bleaching is required. In particular the oxidising compositions for use in the present invention are useful as cleaning compositions for domestic use, in the kitchen or bathroom, floor cleaning, in disinfecting applications for hard surfaces, or sanitising, for example cleaning glass or plastic bottles and pipe cleaning.

The scouring type hard surface cleaner will be a solid oxidising composition in which at least part of the cleaning action is provided by abrasion due to particulate solids. Thus, the compositions of the present invention may contain particulate solids which are inert in aqueous, acidic conditions, for example plastic beads, such as polystyrene or polypropylene, celite and/or talc particles. A preferred composition comprises either solid or liquid encapsulated bleach activator (preferably solid bleach activator such as TAED) , water-soluble, solid builder and/or acidifier with surfactant.

The general purpose liquid cleaning oxidising compositions for use in the present invention may be pourable liquids, which are aqueous or non-aqueous, or may be in gel or paste form. The compositions may be two- phase, for instance in a cream form. In such liquid formulations, thickeners may be included to produce a product having a viscosity such that the oxidising compositions can be contacted with a hard surface and will remain there for a short time, sufficient to give effective bleaching, even if the surface is not horizontal. Suitable thickeners include those which are well known in the art. Examples include gums, such as gum arabic, xanthan gums, guar gum, gelatin, electrolytes (in combination with surfactant) , urea, triethanolamine and polyacrylates.

The oxidising compositions according to the present invention in the form of a foam or mousse, are advantageous because they enable the contact time with a hard surface to be lengthened so that, even on non-horizontal surfaces, the contact time may be at least five minutes, or even at least ten minutes. Any of the types of oxidising compositions described above preferably include surfactant in an amount of at least 1%, preferably at least 2% by weight of the total oxidising composition, most preferably in an amount of at least 5% by weight, or even at least 7% of the total composition.

The oxidising compositions for use in the present invention may be either low foaming or high foaming and surfactants which give high foam are well known in the art. For oxidising compositions which are desired to be low foaming, and de-foaming agents, such as soap or silicone anti-foams may be included in the compositions. The solid oxidising composition according to the invention are particularly preferred because they have good storage stability, since in general, it is easier to keep the bleach activator and peroxygen donor compound in separate particles, and is easier to isolate other components of the composition from one another and from the bleach components.

In the solid compositions, one or more of the components may be in a granular form and these granules may include agents to increase the rate of dissolution of the compositions upon addition to water. Such dissolution rate enhancers may create efference, for instance, a suitable component may be sodium bicarbonate or other alkaline metal bicarbonates.

The following examples illustrate the invention. In the examples, the concentration of peroxygen source is reported in terms of the starting concentration of aqueous hydrogen peroxide, to which other reactants are added. The molar concentration can be calculated. Example 1 A solution of Flash (Trademark) liquid and a similar solution, but with an added amount of bleach booster mixture formed from TAED (at 1.88 g/ l ) , sodium perborate monohydrate (at 2.58 g/l ) and citric acid in an amount to give a final pH of 6.5, were compared for their performance in bleaching tea stains. Pre-stained tiles were prepared by preparing a solution of black tea, allowing the tea to cool, then immersing unglazed tiles in the tea solution for approximately 30 minutes, removing the tiles and then oven drying them. The solutions were applied with a brush to half a pre-stained tile and then either dipped in water or wiped with a cloth to remove the liquid. The difference in whiteness, as determined using a Hunter-Lab apparatus, in reflectance mode between the two halves was determined. The results are given as ΔW. The Hunter-Lab apparatus was set to CIE tristimulus XYZ scale. The W reading is the Z percentage brightness. The ΔW values for Flash alone, removed by wiping and dipping, were 4.0 and 9.7, respectively. The ΔW values for the boosted Flash were 4.8 and 13.5 respectively. One particular benefit which was observed in this example is that in the tests carried out using the solution of Flash liquid, without bleach booster mixture, after a time delay of a few hours, the tea stain on the cleaned tiles re-appeared, with almost the same stain colour as the untreated stains. In contrast, using the similar solution which included the bleach booster mixture, on drying. several hours later, there was no re-appearance of the tea stain.

Example 2

Solid hard surface cleaner compositions were prepared incorporating the components and in the respective weight percentages listed in table 1. The weight percentage calculations are based on the weight of the total formulation, in each case.

Table 1

FORMULATION 1 2 3 4 Component (wt %)

LABS¹ 9 9 9 9

TAED² 0 3 6 6

CDE³ 3 3 3 3

STPP⁴ 20 20 20 20

CITRIC ACID⁵ 20 10 20 10

PBS1⁶ 10 5 10 10

SYNPERONIC A7⁷ 3 3 3 3

Na SULPHATE⁸ TO 100 TO 100 TO 100 TO 100

1 Arylan SX85 (85% active sodium salt linear alkyl benzene sulphonate) (ex Harcros Chemicals) .

2 Particulate tetra acetyl ethylene diamine activator 3 Ethylan LD (coconut diethanolamide) (ex Harcros

Chemicals) .

4 Sodium tripolyphosphate builder.

5 Solid citric acid builder and acidifier.

6 Sodium perborate monohydrate. 7 Non-ionic surfactant (ex ICI) .

8 Solid sodium sulphate.

Each of formulations 1 to 4 were prepared by dry mixing the ingredients. The Synperonic A7 and CDE were the only liquid components and after mixing, the formulations were friable particulate solid compositions.

Bleaching tests were carried out by dissolving a 25g sample of each formulation in 1 litre of tap water at a temperature of 65-70°C. A brush was dipped into the solution and the liquid was applied to a tea-stained tile prepared as described above. The liquid was only applied to half of each pre-stained tile and the difference in whiteness, as determined using a Hunter-Lab apparatus, in reflectance mode between the two halves was determined. The results are given as ΔW. Again the Hunter-Lab apparatus was set to CIE tristimulus XYZ scale. The W reading is the Z percentage brightness. More than one tile was used for each result and an average of the ΔW obtained.

The results show the good results obtained using the oxidising compositions of the present invention.

Table 2

FORMULATION pH ΔW

1 5 . 35 8 . 5

2 5 . 76 3 . 55

3 5 . 33 13 . 5

4 6. 86 20

Claims

1. A process comprising obtaining an oxidising composition comprising a peroxygen source, an activator compound and at least 2% by weight surfactant comprising non-ionic and amphoteric surfactant, then reacting the peroxygen source with the activator compound which is an acyl donor in a first step in aqueous or non-aqueous solution at a pH below pK_a (1) where pK_a (1) is the pκ_a of the percarboxylic acid corresponding to the acyl group of the activator, to form an oxidising product which is a stronger oxidising agent than the peroxygen source and the product solution is subsequently used as a hard surface cleaner at a pH below pK_a (1) in a second, bleaching step.

2. A process according to any preceding claim in which the first step is carried out at a pH from 5 to 9, preferably from 6 to 8 and most preferably below 7.

3. A process according to any preceding claim in which the peroxygen source is present at a concentration of less than 20M, preferably less than 10M in the reaction mixture.

4. A process according to any preceding claim in which the activator compound is an ester of a C2 or higher carboxylic acid.

5. A process according to any of claims 1 to 3 in which the activator compound is an N-acyl compound having at least 2 carbon atoms in the acyl group.

6. A process according to any preceding claim in which the oxidising composition comprises non-ionic surfactant in an amount of at least 5% preferably at least 6% by weight of the overall composition.

7. A process according to any preceding claim in which in the second step, the product solution contacts the hard surface for a contact time of at least 30 seconds, preferably at least 1 minute, or even 2 minutes.

8. A solid hard surface cleaner composition containing a peroxygen source, an activator, a non-ionic or amphoteric surfactant in an amount of at least 2% by weight based on the total weight of the composition, and if necessary, an acid generating species in quantities such that when all of the components of the composition are added to water the pH is reduced to and remains below pK_a (1) (as defined above) , preferably below pH 7.

9. Use of a composite product according to claim 8 in which when the product is added to water, it forms an acidic solution of peroxygen source, activators, optionally acidifying component and surfactant, having a pH below 7.

10. Use according to claim 9 in which the acidifying component is selected from a polybasic organic carboxylic acid or a compound which drops the pH on reaction with a by-product of the reaction.