Bleaching compositions comprising bromide ions are described in EP-A-24368. The compositions also include a precursor which forms a peracid anion in aqueous solution and the compositions are used as laundry detergents under highly alkaline conditions. It is postulated that the peracid anion generated by the reaction of an activator and a peroxygen source reacts in situ with bromide ions to oxidise them to form hypobro ite and that the hypobro ite acts as the active bleaching component. Bromide regenerated by the bleaching reaction is again oxidised to OBr ^' . Other alkaline bleaching liquors produced by dissolution of compositions containing a peroxygen source and an activator have been described as having biocidal properties, for instance by virtue of the presence of peracid anion generated by reaction of activator and peroxygen source. For instance such utility is disclosed in GB-A-1337858. In GB-A-1566671, other biocides can be added to the composition to supplement the bactericidal

effects of the peracid anion. It is also suggested that the by-product of the reaction creating the peracid formed by hydrolysis of an ester of an aryl hydroxyl group, that is a benzoic acid derivative with a hydroxyl substituent in the ring, has biocidal properties. Caro's acid is mentioned as one of the peroxygen sources.

In US-A-5350563 and in DE-A-3615787, combinations of activators are used with peroxygen sources to achieve improved disinfection. Both activators are said to react with the peroxygen source itself. In both publications the pH appears to be alkaline.

In GB-A-1571357 an anhydride is reacted with hydrogen peroxide at acidic pH, to produce a liquor which is said to be biocidal, partly due to the peracid formed and partly due to the by-product which is a benzoic acid derivative with a hydroxyl group substituted in the ring.

In EP-A-0125781 enol ester activators are used in combination with peroxygen sources as a bleaching composition. The utility of the composition includes biocidal properties and it may be used in recirculating water systems. The compositions may be supplemented with additional biocidal components and in the recirculating water system, as well as acting as a biocide the composition may oxidise other oxidisable components present in the water which it is desired to remove.

In US-A-3551087 wool dyeing processes are described in which hydrogen peroxide is used in combination with formamyde and a formaldehyde source. Formaldehyde is said to be released under the reaction conditions. Performic acid is produced in situ . The aqueous solution formed is used at boiling point. The pH is acidic.

In WO-A-9418299 (not published at the priority date of the present application) , the use of an acyl donor activator in combination with a peroxygen source under acidic conditions is described. It is suggested that co- disinfectants, co-biocides and slimicides may be useful additives for compositions based upon those components.

WO-A-9418297 describes similar products and processes. Worked examples include surfactant-containing compositions as well as citric acid. Citric acid can act as a virucide. SϋFW-Journal, 118 Jahrgang 9/92, p 556-562, describes the study of enzyme mediated generation of microbial compounds in mammalian systems. It is described that in milk, lactoperoxidase uses hydrogen peroxide from lactobacilli or other contaminating microorganisms in milk to oxidise thiocyanate ions to form anti-microbial hypothiocyanate anion. The finding has been used to produce anti-microbial compositions which are described in WO91/11105. The compositions contain iodide and thiocyanate ions which are oxidised in situ using hydrogen peroxide which is produced in situ by an oxidoreductase enzyme, glucose oxidase with its corresponding oxidisable substrate, glucose. It is reported in the article mentioned above that for efficacy an enzymic source of hydrogen peroxide must be used.

Enzymes may provide handling difficulties and efforts must be taken to ensure that they do not lose their activity. Enzymes systems are also very limiting because it is not possible to obtain high concentrations of oxidising agent.

In accordance with the present invention, there is provided a biocidal composition which is a composite product comprising a peroxygen source, an activator for the peroxygen source which is an acyl donor, the acyl group of which has 2 or more carbon atoms, a biocide precursor which is a different compound to the peroxygen source, the activator and the product of the reaction between the peroxygen source and the activator in aqueous solution and which reaction with the reaction product of the peroxygen source and the activator in aqueous solution produces a biocidally active species ("a co-biocide") and if necessary, a pH-modifying component such that when all of the components of the composition are dissolved in aqueous solution, the pH is less than pK,(l), where pK,(l) is the

pH of the percarboxylic acid corresponding to the acyl group of the activator.

The co-biocide produced in situ broadens the biocidal spectrum of the species produced in situ by reaction of the activator and the peroxygen source.

The activator may be an N-acyl or an O-acyl derivative. Preferably the activator is a compound of the formula I

O

R -C-L I 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, alkenyl, 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 to 13, preferably 7 to 11, most preferably 8 to 11. It is preferred that R is an aliphatic group preferably a . _u alkyl group, a C^^-alkenyl or an aryl group, most preferably a methyl group, a branched or straight chain C ₆ . _1β -alkyl group or a phenyl group.

In the present invention alkyl and alkenyl groups 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 -CH ₂ - 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 heteroato . Substituents on R ¹ and L can include hydroxyl,

»N-R ² in which R ² is selected from any of the groups represented by R ¹ and is preferably lower alkyl, a ine, 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.

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 acylamines, such as TAED. Other examples of N-acyl derivatives are: a) l,5-diacetyl-2, 4-dioxohexahydro-l,3,5-triazine

(DADHT) ; b) N-alkyl-N-sulphonyl 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 aleic acid hydrazide; d) θ,N,N-trisubstituted hydroxylamines, such as O-benzoyl- N,N-succinyl hydroxylamine, 0-p-nitrobenzoyl-N,N-succinyl hydroxyla ine and θ,N,N-triacetyl hydroxylamine; e) N,N'-diacyl sulphurylamides, for example N,N'-dimethyl- 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 i,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, ')-diacety1 malonamide. k) 0,N,N-trisubstituted alkanolamines, such as 0,N,N- triacetyl ethanolamine. 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 C ₄ . 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 tribenzoy1cyanurate, q) esters giving relatively surface active oxidising products for instance of C _j .^-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^^-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 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, maleic, 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

.r- 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 Q' is selected from the same groups as Q and R ..3 ^J is H, alkyl, aryl, alkaryl, aralkyl, alkoxyl, haloalkyl, a ino, aminoalkyl, carboxylic group or a carbonyl- containing function; preferably 2-methyl-(4H)3,l-

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 WO- A-9306203.

Mixtures of activators can be used in the invention. Where mixtures are used then the upper limit of the pH specified for the invention is the higher of the pK _a 's of the peracids corresponding to the two acyl groups, if they are different to one another. For instance a mixture of one activator which is an acetyl derivative with one activator which is a higher alkanoyl or aryl derivative might be useful. The pK _a of peracetic acid is, for example 8.2, whilst that of performic acid is 7.1 and that of peroxy benzoic acid is 7.6.

The activator may be a compound which is a solid at room temperature, for instance which has a melting point of at least 40°C, preferably at least 50°C, for instance higher than 60°C. The peroxygen source may be hydrogen peroxide itself, or 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. Particularly preferred peroxygen sources are sodium perborate, sodium percarbonate, or even Caro's acid (monopersulphuric acid) or salts thereof. Where Caro's acid is the biocide precursor another compound must be used as the peroxygen source. Mixtures of any of these peroxygen sources may also be used. The biocide precursor is any component which can be reacted with the product mixture of the reaction between the peroxygen source and the activator to provide a biocidally active species, the co-biocide. The benefit of this is that one can use a biocide precursor which does not react or not at a significant rate, with the either the peroxygen precursor itself or the activator especially at ambient temperatures. The reaction of the biocide

precursor is believed to be with the stronger oxidising compound formed upon the reaction between the peroxygen source and the activator (which product is believed to be the percarboxylic acid derived from the acyl group of the activator, or its anion) is believed to be an oxidation reaction. For instance, it is believed that a halide ion is oxidised to form an active halogen species Hal ₃ , or hypohalite OHal ^" , which are potent disinfecting agents. The biocide precursor may itself have some biocidal properties, but such properties are generally less potent than the biocidal properties of the biocidal species i.e. the co-biocide formed upon its reaction with the product of the reaction between the activator and the peroxygen source or else are not exhibited for at the pH's specified for the use step of the present process. For instance Caro's acid acts as a biocide precursor but has some biocidal properties itself. Examples are any component which is a source of halide ions in aqueous solution, such as bromide, chloride or iodide ions or iodophors. The biocide precursor may also be Caro's acid (monoperoxysulphate) which reacts with the product of the reaction between an activator and a peroxygen source, though not with either compound individually, to form a product which is a highly potent biocide. In one preferred embodiment of the composite product the activator is TAEO. 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.

The present invention also includes a process comprising reacting a peroxygen source with an activator compound which is an acyl donor the acyl group of which preferably has at least 2 carbon atoms in a first step in aqueous solution to form a product solution comprising an oxidising product which is a stronger oxidising agent than the peroxygen source itself, and in a second step, a

biocide precursor is oxidised by the oxidising product to form a biocidal species in a final solution and in a third step, using the final solution as a biocidal composition at a pH below pK _a (l) where pK _a (l) is the pK _a of the percarboxylic acid corresponding to the acyl group of the activator. Preferably, the biocide precursor is present in the first step, during the reaction between the peroxygen source and the activator compound. Preferably the peroxygen source and activator compound are reacted in aqueous solution. Preferably the first step is also at a pH below pK _a (l) .

The present invention is particularly advantageous because a wider range of biocidal species formed by oxidation are made available and can be made in situ from storage stable compositions.

The pH in the first and third steps is preferably acidic, more preferably less than 6.5. The pH in the perhydrolysis step is usually more than 2.0.

The composite product which may provide the components for the first step, may contain a pH-adjusting component usually an acidifying component. Where an additional acidifying component is used, it may be an acid and/or buffering material. The component may comprise a polybasic organic acid, such as a polybasic carboxylic acid such as succinic or adipic acid, in addition to citric and/or sulphamic acid. 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, e.g. cis-l,2-diols, such as glycols and polyols, boric acid or sodium dihydrogen phosphate can be used.

In a particularly preferred embodiment of the invention, the composition may also comprise an additional biocidal component, such as silver salt. The silver salt is preferably present in concentrations less than the solubility limit of silver. In order to enable higher

concentrations of silver ions to be used, the silver ions may be present as silver complexes which are stable and soluble in aqueous solution.

Silver salts are particularly preferred as an additional biocidal component as they increase the range of biocidal activity of the solutions produced and provide a synergistic biocidal effect when used in combination with the biocidal species formed from a halide ion or from thiocyanate. Particularly preferred silver salts for incorporation into the product solution include silver thiocyanate, silver ammonium iodide or any other soluble silver halide complex. In a particularly preferred embodiment of the invention, the additional biocidal components if present in the first step, in which the peroxygen source and activator compound are reacted.

Where included the concentration of silver ions or other additional biocidal components will be such as to produce a biocidal effect in the final solution. For silver ions, in the final solution, their concentration may be from O.OOlg/1, generally from 0.01, or even O.lg/1. Preferably their concentration will not exceed 50g/l or most preferably 20g/l.

Stabiliser may also be included in the compositions and processes of the invention, which will increase the storage stability of the peroxide and/or the silver ions which may be light sensitive.

In the perhydrolysis reaction of the first step 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. 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.

Since there is generally no addition of acidifying compound or of base between irst and third steps and since both are preferably in the same pH range (of less than pK _a (l), preferably acidic) the pH in the second step is usually also in the same range. The pH may vary, usually becoming more acid as the reaction between the various components takes place. The present invention allows the formation of an aqueous biocidal liquor containing a blend of biocidally active species, one of which is the oxidising product from the first step. The activator and peroxygen source are therefore present in amounts so as to form the oxidising product in a stoichiometric excess over the biocide precursor so that there will be at least some biocide which is the oxidising product formed in the first step and at least some co-biocide which is formed from the biocide precursor by its reaction in the presence of the product mixture of the first step of the process of this invention.

The biocidal liquor obtained in this way has improved properties. The combination of biocidal components can give a broader spectrum of activity against microbes, for example against bacteria with potential to cause infection. It also allows the compositions to have utility over a wider range of use conditions, than the individual biocides, such as of temperature components. The compositions are therefore highly effective.

The biocidal activity of the final solution may be optimised for a particular application by changing the relative amounts of peroxygen source, activator, biocidal precursor and optional additional biocidal component.

In the first and/or second 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 ^β C or even around room temperature. The temperature is often above 20°C. The temperature in the second and third steps is likely to be somewhat lower than the temperature in the first step, due to cooling either prior to or on application of the product of the third step to a substrate to be treated with biocide. Preferred temperatures for the third step are preferably in the same ranges as the temperature during the perhydrolysis (first) step and is preferably substantially the same temperature. 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. Also the rate of perhydrolysis reaction can be controlled by adjusting the temperature.

In the process of the invention it is possible for there to be a time delay between the first and second steps or between the second and third steps. For instance the peroxygen source and the bleach activator may be allowed to react in aqueous conditions in the presence of the biocide precursor for at least five minutes, up to one or two days, suitably in the range ten minutes to one day such that the second step takes place and there is a time delay before the third step ie the use as a biocidal composition of the final solution. However, the biocidal species may be relatively short lived and if so, there is preferably no greater than a short time delay between the second and third steps. Therefore, either the biocide precursor must not be added to the product solution until shortly before use, or the time delay between the second and third steps must not be so long that the biocidal species produced has substantially lost its biocidal properties. The biocide

precursor is present in the first step so that the first and second steps are substantially simultaneous. The time delay between the second and third steps is preferably no greater than 2 hours, preferably less than 1 hour or even 30 minutes. The peroxygen source, bleach activator and biocide precursor may be mixed together and added to water simultaneously, or alternatively they may be added to water one after the other or in various combinations. They may be added to water and used immediately. The third step in accordance with the process of the present invention in which the final solution is used as a biocidal composition may comprise application in any situation where a disinfectant or biocidal cleaning step is required usually of hard surfaces. For example the final solutions prepared according to the invention may be used in domestic or institutional applications, for example in kitchens and bathrooms or, may be used in medical applications. Further examples are given below.

Although the composite product 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 another of which contains the pH-modifying component, it is preferred to provide at least the activator and pH-modifying 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 for all of the components to be provided in a single composition, in which the components do not react.

The produc (s) 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.

Preferably the composition or each composition of the composite product 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.

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 150%, preferably up to 100%, or most preferably up to 80% of the stoichiometric amount of activator (for complete reaction with the peroxygen source) is provided.

The product solution may require surface active properties. Where they are required, the composite product may comprise a surfactant. Any conventional surfactant may be used, selected from non-ionic, anionic, cationic, and amphoteric surfactants. However, non-ionic and amphoteric

surfactants are preferred as they are more resistant to changing conditions of pH.

Suitable nonionic surfactants include for example alkanolamides (such as CIO to C20) and/or ethoxylated alcohols, carboxylic acids, amines, alcohol amides, alcohol phenol, glyceryl esters, sorbitan esters, phosphate esters etc.

Suitable amphoteric surfactants include for example betaines, such as alkyl betaines, sulphobetaines, and also imidazoline derivatives.

Suitable cationic surfactants include for example quaternary amines, imidizolines and quaternised imidizolines.

In one particularly preferred embodiment a biocidal cationic surfactant is used which provides an additional biocidal species in the final use liquor the product of the third step. A cationic surfactant may, for instance, have a halide counterion associated with it and the halide counterion can act as the biocide precursor required in the present invention. This embodiment thus gives a highly advantageous combination of active ingredients.

Suitable anionic surfactants include any surfactant useful in a detergent for example salts of sulphonic or monoesterified sulphuric acids, 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.

The composite product may include other additives, for instance stabilisers which stabilise the composite product on storage as well as stabilisers for the oxidising species formed in the first step of the process, such as a heavy metal sequestrant chelating agent. One or mixtures of more than one chelating agent can be used. Particularly preferred chelating agents are alkylene poly(amine carboxylic acids), alkylene poly(alkylene aminophosphonic acids) and their salts especially ethylenediamine

tetraacetic acid (EDTA) , diethylene triamine pentaacetic acid (DTPA) , diethylenetriamine penta( ethylene phosphoric acid) (DTPMP) and ethylenediamine tetra(methylene phosphonic acid) (EOTMP) . 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 for example the mode of use of the composition. Examples are perfumes, or agents to assist dissolution or dispersion of the product into water or inorganic or enzymatic catalysts.

The reaction product of the reaction in the first and second steps is preferably used immediately, without removal of any by-products or addition of other materials, in the third step in which it is used as a biocide.

The composite product 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 composite product of the present invention may be either solid or liquid. For example, they may be pourable liquids which are aqueous or non-aqueous. Thickeners may be included in a liquid product to increase viscosity, such as those which are well known in the art, including gums, electrolytes (in combination with surfactant) , urea, triethanolamine and polyacrylates.

Since the process steps of the present invention can be carried out at a relatively low concentration they can be carried out without special precautions, for instance in a domestic or institutional environment. The composite products themselves prior to dissolution or dispersion in water may be non-hazardous to handle.

Compositions which are suitable to be diluted direct into water to allow the first and second steps of the reaction to proceed without further additions, may be categorised in four convenient categories.

The first category comprises liquid formulations which include a surfactant. These compositions will be suitable for use as hard surface cleaners and other uses where surface active disinfection is required, for instance floor cleaning compositions, domestic and institutional hard surface cleaners, toilet disinfectants, general toiletries disinfectant, sanitising bottles, including glass and plastic bottles, and pipe cleaning compositions. For most of these uses it will be desirable for the composition to be relatively low foaming, although for some, for instance toilet disinfecting and general toiletries disinfectant, it may be desirable for the composition to have a relatively high foam. The use of suitable surfactants which will foam is well known in the art. For compositions which are desired to be low foam, it may desirable to incorporate anti-foaming agents, for instance soap or silicone anti- foams.

A second category of composition comprises liquid formulations but which contain no surfactants. These may be useful where no surface activity is necessary, for instance in effluent and water treatment, in toilet disinfectants, for use as a swimming pool treatment in general industrial sterilisation and in some domestic sterilisation situations, for instance as a general toiletry disinfectant, in denture cleaning compositions, in sanitising glass and plastic bottles or other containers, as well as in certain environmental clean-up operations.

The liquid formulations mentioned above may be pourable liquids, which are aqueous or non-aqueous, or may be in gel or paste form. Furthermore the compositions may be two-phase, for instance a cream form. Alternatively the compositions could be in the form of a mousse (where the composition contains surfactant) by the injection of a gas, especially for domestic hard surface cleaning operations. A further category of composition is in solid form and includes a surfactant. The general uses of these compositions are similar to those for which the liquid

formulations including a surfactant are useful, as mentioned above.

A further category of formulation comprises a solid composition but without surfactant. These compositions are useful in the same categories of uses as the liquid formulations without surfactant. The compositions may, in solid form, be more storage stable, since it is in general easier to keep the bleach activator and peroxygen donor compound in separate particles and prevent them coming into contact with one another during storage. It is furthermore easier to isolate other components of the composition from one another and from the bleach components, especially where storage sensitive compounds such as enzymes, other biocides or perfumes are present. Solid compositions may be in the form of particulate mixtures or may be tabletted. Tabletted formulations, or even granular formulations, may include agents to increase the dissolution rate of the compositions upon addition to water. For instance suitable components known for incorporation into tablets can be used to aid disintegration of a composite product which is a tablet. Such ingredients may create effervescence, for instance; a suitable component is sodium bicarbonate, or other alkali metal bicarbonate, optionally in combination with an acid. The compositions may also contain ingredients to assist in their application or stability or which improve their appearance, for instance thickeners, dispersants, opacifiers, hydrotropes, dyes, perfumes etc.

The present invention may be used to provide a biocidal effect against micro-organisms such as bacteria, fungi, yeasts, moulds and/or viruses.

The final solutions prepared from the biocidal compositions and the processes of the present invention have been found to be surprisingly beneficial across a wide range of bacteria. This is due to the synergistic effect which results from the combination of peroxygen and other, generally halogen-based biocidal species.

The present invention is illustrated in the following examples: Example 1

Aqueous solutions of mixtures of ingredients in the amounts specified in Table 1 below were made up. The solutions were immediately subjected to the British Standard BS6905 Modified Kelsey-Sykes tests for determining disinfection efficacy under dirty Hospital conditions. In the course of the test a bacteria culture, in this case Staph. aureus, is added to solutions of test mixtures at a range of concentrations, five samples are removed at 8, 18 and 28 minutes and placed in a nutrient broth. At the same time a sample of denatured yeast and a further aliquot of bacterium are added to the test solution. The tubes of nutrient broth are assessed for growth or not growth after incubation. For a pass there must be growth in three or fewer of the tubes containing sample removed at 8 and 18 minutes at the recommended dilution.

The results for biocide precursor and other additives are given in Table 2. The numbers given are the tubes in r which growth occurred. The final line is a summary of whether a pass or fail was achieved at the concentration tested. Three concentrations are tested for each formulation. The concentration expected to work is denoted by "x", 50% lower (x-50%) and 50% higher (x+50%) concentrations are also tested. A pass must be obtained at the expected concentration to comply with the British Standard.

IA£LE_L

COMPONENT AMOUNT g/l

FORM

TABD PBS1 Cit Acid NaHCO, 7BO CTAB

1.1 1.88 2.58 3.0 1.54 0 0

1.2 1.88 2.58 3.0 1.54 2.0 0

1.3 1.88 2.58 3.0 1.54 0 2.0

TAED Tetra acetyl ethylenediamine PBS1 Sodium perborate onohydrate

Cit Acid Citric Acid dihydrate

7EO Synperonic A7, nonionic surfactant (ex ICI)

CTAB Cetyltri ethyl ammonium bromide (cetrimide) a cationic surfactant.

TAB E 2

The results show that only the formulation which contains actimide is effective in this test and that the compositions which contain no biocide precursor are inadequate even at high concentrations (x + 50) . Example 2

Further formulations were made up by dissolving mixtures of ingredients specified in Table 3 into 90 ml water, in appropriate amounts so as to give the quoted concentrations of each component in the solution. The mixtures were allowed to stand to allow dissolution of the ingredients for 10 minutes. The solutions were used in a test for bactericidal properties based on the principles of BS6471.1984.

10 ml of a 24 hour Nutrient Broth culture of the appropriate test bacteria was added to the biocide solution (or to distilled water) and allowed to stand, with occasional mixing, for 10 minutes at room temperature. During the test days, room temperature ranged between 60 ^β F and 70 ^β F.

At the completion of the contact period colony counts were performed using Nutrient Agar as the solid recovery medium and Maximum Recovery Diluent (MRD) as the diluent. 1 ml aliquots of the test suspension were transferred to

three test tubes containing 9 ml of MRD. Further 0.1 ml aliquots were spread over the surface of the Nutrient Agar plates. 1 ml aliquots were spread over the surface of the Nutrient Agar plates. 1 ml aliquots were than immediately transferred to three further tubes containing 9 ml of MRD. This rapid 1:100 dilution should minimise the effect of prolonged contact times.

All plates were incubated for 24 hours at 37°C after which time the number of viable colonies on the plates were counted. The results are shown in Table 4.

IA1 E_2.

XAfiLf 4

Teal S APHYLOCOCCUS AUREUS STREPTOCOCCUS FABCAUS Formulation

Mean Colony Percentage Lot Mean Colony Perεeαtaf* Log count (clu/ml) Reduction Reduction count (cni/ml) Reduction Reduction

Water 3.5 x HP - - 237 x 10* - - Coαtrol

2.1 >3.0 x 10» <91.4 <1.070 2.41 x 10* - -

23 < 10.0 >99.99 >5-S44 < I0.0 > 99.99 > 5-544

23 <10.0 >99.99 >5-544 < 10.0 > 99.99 >S-S44 |

Formulation 2.1 which contains no biocide precursor was not effective against either test bacterium.

Formulations 2.2 and 2.3 were both very effective, producing a kill in excess of 99.99% against both test bacteria.

Similar test using halide salts other than iodides show the same effect at equimolar bases (ie replacing iodide with equimolar bromide or chloride) .

Examples 3.1-3.4 - Formulations

The following formulations exhibit effective peracid release and biocidal activity.

3.1) Hard surface cleaner formulation with KI pH 8.0 in solution, tested at 5 q/t and 2.5 q/t

%wt

1.39 g TAED granule 27.8

22..3333 gg PPBBSSII 46.6

1.28 g Citric acid 25.6

0.37 g KI 6.9

0.02 g Dequest 2066

3.2) Medical instrument sterilising formulation with KMPS pH 8.0 in solution, tested at 5 q/t and 2.5 q/t

%wt

1.39 g TAED granule 27.8

2.33 g PBSI 46.6 1 1..2288 gg C Ciittrriicc aacciidd 25.6

0.75 g KMPS 13.0

0.02 g Dequest 2066

3.3) Pipe cleaning formulation with QUAT pH 8.0 in solution, tested at 5 q/t and 2.5 q/t

%wt

1.39 g TAED granule 27.8

2.33 g PBSI 46.6

1.28 g Citric acid 25.6 0.75 g Benzalkonium chloride 13.0

0.02 g Dequest 2066

3.4) Disinfectant formulation pH 8.0 in solution, dosage 5 q/t and 2.5 q/t %wt

1.39 g TAED granule 15.2

2.33 g PBSI 25.5

1.53 g Citric acid 16.8

1.25 g Benzalkonium chloride 13.7

0.88 g Sodium sulphate 9.6

0.75 g Sodium carbonate 8.2

0.02 g Dequest 2066