EP0944705A2

EP0944705A2 - Improvements relating to bleaching compositions comprising hydrogen peroxide

Info

Publication number: EP0944705A2
Application number: EP97950132A
Authority: EP
Inventors: Katherine Mary Thompson; David William Thornthwaite
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1996-11-29
Filing date: 1997-10-31
Publication date: 1999-09-29
Also published as: TR199901906T2; KR20000069188A; HUP0000322A2; AR009640A1; GB9624840D0; HUP0000322A3; AU5319598A; SK69999A3; WO1998023717A2; IN189585B; CN1245525A; WO1998023717A3; AU740952B2; BR9713453A; JP2001504880A; ZA9710143B; CA2273168A1

Abstract

The invention provides a bleaching composition of pH 10-14 which comprises an oxygen transfer agent and hydrogen peroxide. It is believed that the reaction of hydrogen peroxide with the imine quat. oxygen transfer agents proceeds through a different route than that of the organic and inorganic peroxides. As a consequence, the formation of acyl hydroxamate is significantly reduced. Furthermore it is believed that when hydrogen peroxide is used as the bleaching agent in the pH range indicated, a surprising improvement in the efficacy of the bleaching system occurs and it is possible to formulate peroxide based systems which have efficacy approaching or exceeding that of hypochlorite without the disadvantages associated with hypochlorite. A further aspect of the present invention provides a method for bleaching a stained substrate which comprises the step of treating the substrate with a bleaching composition of pH 10-14, which bleaching composition comprises an oxygen transfer agent and hydrogen peroxide.

Description

IMPROVEMENTS RELATING TO BLEACHING COMPOSITIONS COMPRISING HYDROGEN PEROXIDE

Field of the Invention

The present invention relates to bleaching compositions comprising hydrogen peroxide.

Background to the Invention

In household cleaning, fabric washing and in many other areas there is a general need for agents which can 'bleach' unsightly materials, i.e. which can react with these materials to decolourise them. One of the commonest of such bleaching agents is sodium hypochlorite, which is widely used in cleaning compositions to decolourise soils, to assist in cleaning through its reaction with soils and to kill micro-organisms .

Sodium hypochlorite is a powerful oxidising agent, which can decolourise a very large number of coloured compounds found in soils but which has significant limitations when used to bleach certain fatty and pyrolised soils. Many consumers prefer not to use chlorine-based bleach compounds due the characteristic and pungent smell of chlorine. In some circumstances the use of a chlorine containing bleaching composition must be avoided due to the possibly adverse effects of mixing such compositions with acidic bathroom cleaners and the resulting release of chlorine gas. There is a need for an alternative to chlorine-based bleaching and bleaching/cleaning agents. One well known class of alternatives are the peroxygen compounds. While these have been used extensively as bleaching and cleaning agents, the efficacy of peroxygen compounds as bleaching agents falls short of that of hypochlorite. There is therefore a general need to find new alternatives to chlorine based bleaching agents and to improve the properties of these towards that of hypochlorite.

It is known to use oxygen transfer agents such as ' imine quat ' compounds to promote the bleaching activity of peroxygen compounds. In the context of the present invention, an oxygen transfer agent is a species which reacts with a peroxygen compound such as hydrogen peroxide to form an oxidative bleaching species which oxidative bleaching species, subsequently reacts with a substrate to regenerate the oxygen transfer agent.

Such oxygen transfer agents include N-methyl-3.4- dihydroisoquinolinium salts. US 5360569 discloses that imine quat molecules can be used to promote the activity of TAED/perborate bleaching compositions.

These systems are believed to work by generating per- acetic acid in situ. This organic peroxide is believed to interact with the imine quat. to bring about the bleaching activity. US 5360568 discloses that imine quat molecules can be used to promote the activity of monopersulphate (an inorganic peroxygen compound) and peroxy-adipyl-phthalimide (PAP) (an the organic peracid) . In the above-mentioned compositions the imine quat is believed to be converted, by reaction with the peracid into an oxaziradiniu salt which can act as an oxygen donor (i.e. a bleaching species) and which is converted back into the imine quat. The oxaziradinium ion is however unstable at high pH in the compositions described above, where it is believed to be converted into an acyl hydroxamate thereby preventing the bleaching cycle from working efficiently. As a result, compositions have been limited in pH range and it has proved difficult to formulate compositions which are effective against the more recalcitrant stains particularly hydrophobic and/or pyrolised stains .

Brief Description of the Invention

It is believed that the above-mentioned problem is overcome by the use of hydrogen peroxide, rather than an organic peracid or an inorganic peroxide, as the source of oxidising equivalents. This enables the formulation of compositions to bleach at relatively high pH's where some of the more difficult stains are soluble and hence accessible to the formulation.

Other, hitherto unsuspected benefits arise from the use of hydrogen peroxide as are described below.

Accordingly, the present invention provides a bleaching composition of pH 10-14 which comprises an oxygen transfer agent and hydrogen peroxide.

Without wishing to limit the scope of the present specification by reference to some theory of operation, it is believed that the reaction of hydrogen peroxide with the imine quat. oxygen transfer agents proceeds through a different route than that of the organic and inorganic peroxides mentioned above. As a consequence, the formation of acyl hydroxamate is significantly reduced. Furthermore it is believed that when hydrogen peroxide is used as the bleaching agent in the pH range indicated, a surprising improvement in the efficacy of the bleaching system occurs and it is possible to formulate peroxide based systems which have efficacy approaching or exceeding that of hypochlorite without the disadvantages associated with hypochlorite.

A further aspect of the present invention provides a method for bleaching a stained substrate which comprises the step of treating the substrate with a bleaching composition of pH 10-14 which bleaching composition comprises an oxygen transfer agent and hydrogen peroxide.

Detailed Description of the Invention

As noted above, hydrogen peroxide is an essential component of the compositions according to the present invention. As hydrogen peroxide is a reactive species, this will place some limitations on the other components which can be present. These are described in greater detail below.

Hydrogen peroxide is preferably present at a level of 0.5-10%wt on product, more preferably l-5%wt on product. In typical embodiments of the invention the weight ratio of the hydrogen peroxide to the oxygen transfer agent falls in the range 5:1 to 20:1. Oxyσen Transfer Agents

Oxygen transfer agents for use in the present invention, include, but are not limited to, the imine quat. N-methyl-3.4-dihydroisoquinolinium salts. Where these salts are used, suitable counter-ions include halides, sulphate, methosulphate, sulphonate, p-toluene sulphonate and phosphate. Oxygen transfer agents which comprise a quaternary nitrogen atom are preferred.

A broad class of oxygen transfer agents suitable for use in embodiments of the present invention are compounds comprising ions of the general structure:

(R_j) !R,)C=N (R, : R.

Wherein:

R_χ and R₄ are in a cis- relation and are substituted or unsubstituted moieties selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl and cycloalkyl radicals:

R₂ is a substituted or unsubstituted moiety selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl, cycloalkyl, nito, halo, cyano, alkoxy, keto, carboxylic acid and carboalkoxy groups :

R₃ is a substituted or unsubstituted moiety selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl, cycloalkyl, nito, halo and cyano groups : Preferably, R_χ with R₂ and R₃ respectively together form a moiety selected from the group consisting of cycloalkyl, polycyclo, heterocyclic and aromatic ring systems .

Heterocyclic rings according to the present specification include cycloaliphatic and cycloaromatic type radicals incorporating an oxygen, sulphur and/or nitrogen atom within the ring system. Representative nitrogen heterocycles include pyridine, pyrrole, imi- dazole, triazole, tetrazole, morpholine, pyrrolidone, piperidene and piperazine. Suitable oxygen heterocycles include furan, tetrahydrofuran and dioxane. Sulphur heterocycles may include thiophene and tetrahydrothiophene.

The term substituted as used in relation to R_χ/ R₂, R₃ and R₄ includes a substituent which is nitro, halo, cyano, C1-C20 alkyl, amino, aminoalkyl, thioalkyl, sulphoalkyl, carboxyester, hydroxy, C1-C20 alkoxy, polyalkoxy, or C1-C40 quaternary di- or tri-alkyl ammonium.

Preferred oxygen transfer agents are quaternary imine salts, particularly those set forth in US patent specification 5,360,568 (Madison and Coope) , more particularly the substituted or unsubstituted isoquinolinium salts, preferably the 3,4 di-hydro isoquinolinium salts and more preferably the N-methyl 3,4 di-hydro-isoquinolinium salts. N-methyl 3,4 di- hydro-isoquinolinium p-toluene sulphonate is a particularly preferred oxygen transfer agent.

Typically, the oxygen transfer agents are present of levels of 0.001-10%wt on product. Preferably, the oxygen transfer agents are present at levels of 0.01- l%wt on product, more preferably 0.1-0.5%wt on product .

Surfactants

It is preferred that the compositions according to the invention further comprise one or more surfactant species. Surfactants can be nonionic, anionic, cationic, amphoteric or zwitterionic provided that they, and where appropriate their counter-ions, do not react substantially with the oxygen transfer agent or the hydrogen peroxide.

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements .

Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 3 to 10 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 3 to 10 moles of ethylene oxide per mole of alkylphenol .

The preferred alkoxylated alcohol nonionic surfactants are ethoxylated alcohols having a chain length of

C9-C11 and an EO value of at least 3 but less than 10. Particularly preferred nonionic surfactants include the condensation products of C_χo alcohols with 3-8 moles of ethylene oxide. The preferred ethoxylated alcohols have a calculated HLB of 10-16. An example of a suitable surfactant is ' IMBENTIN 91-35 OFA ' (TM, ex. Kolb AG) a C₉__n alcohol with five moles of ethoxylation.

Alternative surfactants include amine oxides, amines and/or ethoxylates thereof. Amine oxides with a carbon chain length of C12-C14 are particularly preferred.

When present, the amount of nonionic detergent active to be employed in the composition of the invention will generally be from 0.01 to 30%wt, preferably from 0.1 to 20%wt, and most preferably from 3 to 10%wt for non-concentrated products. Concentrated products will have 10-20%wt nonionic surfactant present, whereas dilute products suitable for spraying will have 0.1-5%wt nonionic surfactant present.

ES

As noted above the pH of compositions according to the present invention falls in the range 10-14. pH of compositions is preferably 10-12, more preferably 10-11. At these higher pH's we have found that the composition penetrates more readily into the soils. As is noted in the illustrative examples given below, the use of oxygen transfer agents at high pH is contra-indicated by their tendency to increase the colour of a stain rather than reduce it.

Minors

Minor components of compositions according to the present invention include those typically present in cleaning compositions.

In compositions which contain hydrogen peroxide it is useful to include a metal ion complexing agent to retard decomposition of the peroxide by any metal ions which may be present as contaminants or such as are introduced during processing. Again, these components should be selected such that they do not react do not react substantially with the oxygen transfer agent or the hydrogen peroxide.

Preferably, cleaning and/or disinfecting compositions according to the invention will further comprise metal ion sequestrants such as ethylene-diamine-tetra- acetates, amino-polyphosphonates (such as those in the DEQUEST (TM) range) and phosphates and a wide variety of other poly-functional organic acids and salts, can also optionally be employed. Preferred metal ion sequesterants are selected from dipicolinic acid, ethylene diamine tetra acetic acid (EDTA) and its salts, hydroxy-ethylidene diphosphonic acid (Dequest 2010, RTM) , ethylene diamine tetra (methylene phosphonic acid) (Dequest 2040, RTM), diethylene triamine penta (methylene phosphonic acid) (Dequest 2060, RTM), amino tri (methylene phosphonic acid) (Dequest 2000, RTM). The phosphonic acid derivatives are particularly preferred. It is preferred that the level of phosphonic acid derivative metal ion complexing agent should fall into the range 0.05-5%.

Preferably, cleaning and/or disinfecting compositions according to the invention will further comprise at least 1% of a solvent of the form R_χ-0- (EO) _m- (PO) _n-R₂, wherein R₁ and R₂ are independently C2-6 alkyl or H, but not both hydrogen, m and n are independently 0-5. More preferably, the solvent is selected from the group comprising di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether, isopropanol, ethanol, butanol and mixtures thereof. Typically, the level of solvent in cleaning and disinfecting compositions is 1-10%, with a solvent: nonionic ratio of 1:3-3:1 being particularly preferred.

Where compositions according to the present invention are liquids, they can be water-thin or thickened. Thickened compositions are advantageous in that they cling to sloping surfaces and find particular utility in toilet cleaners. Slight thickening of the composition is desirable for applications in which the composition is sprayed, so as to reduce the extent to which small droplets are produced which might otherwise cause respiratory irritation to the user. Suitable thickening agents include amine oxide and soap and systems based on nonionic surfactants.

Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients such as, colourants, optical brighteners, soil suspending agents, detersive enzymes, gel-control agents, freeze- thaw stabilisers, further bactericides, perfumes and opacifiers .

A particularly preferred compositions according to the present invention comprises a bleaching composition having a pH of 10-12, said composition being an aqueous liquid and comprising:

a) hydrogen peroxide at a level of 0.5-10%wt on product,

b) 0.001-10%wt on product of an isoquinolinium salt,

c) 0.01 to 30%wt on product of at least one nonionic surfactant, and,

d) optional minors selected from the group consisting of metal ion sequestering agents, solvents and perfumes.

Product form

Products according to the present invention are generally liquids and preferably aqueous. However, other product forms including pastes and solids are also envisaged.

As will be appreciated, the product form is largely determined by the end use and consequently liquids are generally suitable for use as hard surface cleaners, including cleaners for industrial, institutional and domestic cleaning and/or disinfection of hard surfaces including metal, plastics materials or other polymers, ceramic, and glass surfaces.

It is envisaged the method of the present invention can be applied in the cleaning of surfaces used for the preparation of food and beverages (e.g. worktops, conveyor systems and utensils) or other industrial, institutional and domestic surfaces such as sanitary- ware, industrial, institutional and domestic fluid supply applications, for disinfection of medical, surgical or dental apparatus, equipment, facilities or supplies, catheters, contact lens', surgical dressings or surgical instruments, in horticultural applications, e.g. for sterilising the surfaces of greenhouses, for soft surfaces including fabrics

(including in dressings, wipes and cloths) , and nonliving materials of biological origin (such as wood). Solid product forms are suitable for use as toilet and urinal blocks and other uses where slow or delayed release of the components is required.

In order that the present invention may be further understood it will be described hereinafter by reference to illustrative and non-limiting examples and comparisons.

EXAMPLES

The following examples were performed using model kitchen soils and a soiling procedure as described below. The soils were chosen to have recalcitrant stains, which would be difficult to bleach due to the hydrophobic or pyrolised nature of the stain. Example 1: Curcumin/oil stain on formica (TM) .

Soil preparation

Flat tiles, measuring 4" x 4", are cut from white

Formica sheeting and their surfaces thoroughly cleaned using a commercially available liquid abrasive cleaner, 'Jif (TM) . After rinsing with demineralised water, the tiles are allowed to dry at room temperature.

The curcumin/oil stain is prepared by mixing 19 g of vegetable oil and 180 g of ethanol and then adding 1 g of pure curcumin (a pigment found in curry powder) . After thorough stirring, the resulting solution is sprayed onto the tiles using an airbrush propellant canister so as to give a uniform surface coverage. The tiles are left to dry for a minimum of 10 minutes, during which time the ethanol evaporates leaving a bright yellow, slightly sticky, oily stain, which cannot be removed by wiping or rinsing with water. Curcumin is susceptible to photo-oxidation and stained tiles should not be stored for periods exceeding 2 hours before use.

Preparation of Bleach or Surfactant Solutions

Experiments were performed with hydrogen peroxide, PAP (peroxy-adipoyl-phthalimide) , peroxymonosulphate and sodium hypochlorite (a well known inorganic bleaching agent) .

Bleach solutions are prepared by dissolving the peroxide co-oxidant in demineralised water and, where necessary, adding the oxygen transfer agent. Sodium

-3 hydroxide solution (5 o1 dm ) is added dropwise to adjust the pH to the desired value, as determined using a pH meter. Further demineralised water is added to the solution to give the desired final volume.

In the examples described the oxygen transfer agent was N-methyl 3,4 di-hydro isoquinolinium p-toluene sulphonate. The preparation of this material is described in US 5360569 and US 5360568 which are incorporated herein by reference. The material is referred to below as the ' Imine Quat ' .

Hydrogen peroxide solutions are prepared to achieve a

-3 final concentration of 3 w/w % (0.88 mol dm ) and used in conjunction with a 1% molar equivalency of the Imine Quat catalyst (0.0088 mol dm^"3, 0.30 w/w %) . Solutions of potassium Caroate (TM: 6 w/w%, equivalent to 3 w/w%, 0.2 mol dm peroxomonosulphate) and PAP (6-

[N-phthalimido] -perhexanoic acid: 2 w/w%, 0.012 mol dm ) were examined in combination with the same level of Imine Quat. The potassium peroxymonosulphate system was examined at pH 8.5 (but higher pH values were used for hydrogen peroxide (which has a higher pK ) and PAP (which is relatively insoluble at lower alkalinities) . Addition of a wetting agent (1% butyl digol (TM) : diethylene glycol mono n-butyl ether) further increases the PAP solubility.

The bleach systems are compared with the detergency obtained using a C..^ EO_s nonionic surfactant, Imbentin 91-35 OFA (TM) in the formulations listed in TABLE 1 below. In some instances a solvent 'Butyl Digol' (TM) , di-ethylene glycol mono-n-butyl ether, was added or used for comparison.

Soil removal experiments

Examples were performed at room temperature. A glass ring, of diameter 50 mm and height 15 mm, is placed over the centre of the stained tile and 5 cm³ of the aqueous bleach or surfactant solution is pipetted within the annulus of the ring. The solution is allowed to remain in contact with the stained tile surface for 30 seconds, after which the glass ring is removed and the solution poured away. The tile is immediately rinsed with demineralised water for a further 30 seconds and then allowed to dry. Each solution is used to treat two tiles.

The extent of stain removal is assessed visually by a panel of at least 15 people, using a standard scale.

Tiles are graded on an integer scale ranging from 0 to 5, where 0 denotes no visible soil removal and 5 corresponds to total removal . A minimum of two stained tiles are treated with each bleach solution and mean scores for each system are calculated by averaging the scores from both tiles.

Results are shown in TABLE 1 below. From the results presented in TABLE 1, it can be seen that a significant improvement as regards hydrogen peroxide bleaching is obtained in the presence of the Imine Quat at both pH 10 and pH 10.5. A similar increase is not seen for either the organic or inorganic peroxy acid. Comparing the results with conventional cleaning/bleaching systems. It can be seen that use of an oxygen transfer agent together with hydrogen peroxide provides results which are very favourably comparable with hypochlorite, and significantly better than alkali and surfactant based systems.

TABLE 1

Example 2; Baked fat/flour on enamel

Soil preparation

Oleic acid (1 g) , stearic acid (1 g) and Friol (TM) Italian Oil (38 g) are mixed in a metal beaker and directly heated, using a hotplate, to a temperature of 60°C, so that the mixture liquifies. Demineralised water (100 g) is boiled and allowed to cool to 60°C before mixing with Italian flour (40 g) to make a thick paste.

The organic acid-oil mixture and the flour paste are placed in a liquidiser jug and demineralised water (280 g) added. The fat-flour mixture is blended for 5 seconds, allowed to stand for 10 seconds and then blended for a further 5 seconds. The contents of the liquidiser are then transferred to a glass beaker and gently warmed by direct heating over a hot-plate. The mixture is allowed to simmer for five minutes with constant agitation from an overhead stirrer. The mixture must not be allowed to stick to the beaker or excessive cross-linking will occur, resulting in a soil that is overly resistant to removal. The mix is then transferred to a polythene beaker and allowed to cool before use.

Soil application

White enamel tiles (100 mm x 100 mm) are cleaned using a commercially available liquid abrasive cleaner ('Jif¹ [TM] ) , rinsed in demineralised water and allowed to dry. The tiles are then coated with a thin { c. a . 0.5 mm) layer of the fat/flour mix using a screen printing technique. A flexible rubber paddle is used to spread the mix onto the tile surface, through a thin plastic mesh, taking care to achieve a uniformly thin coverage. The soiled tiles are allowed to stand overnight in the open air, acquiring a uniform matt finish. The tiles are baked on the o middle shelf of an oven at 190 C for one hour, developing a light brown colouration, and allowed to cool for 2 hours before cleaning. As there is expected to be variation between batches of these tiles soiled and subsequently pyrolised, it is important that comparisons are performed with tiles taken from the same batch.

Preparation of Bleach and Surfactant Solutions

Solutions are prepared as described for the curcumin- oil soil removal experiments described above with reference to TABLE 1 using the formulations listed in TABLE 2 below. Detergency effects have been studied using Neodol 91-5 (TM) nonionic surfactant, a commercially available, slightly less pure, version of the Imbentin 91-35 OFA (TM) surfactant used in the curcumin/oil experiments above. Admox 10 (TM) is a C₁₀ amine oxide surfactant.

Peracetic acid is used at a concentration equal to that of the HOO active oxidising species present in the 3% hydrogen peroxide solution at the same pH

(10.0) . Soil removal experiments

Soil removal is carried out using a standard Wool Industries Research Association Abrasion Tester (WIRA: TM) apparatus. Two soiled tiles are cleaned simultaneously with the same solution, to provide duplicate results. The bleach or surfactant solution

3

(20 cm ) is poured onto the surface of the tile, and rubbed using a cleaning head covered with two layers of clean ' J' -cloth (TM) material. Each tile is cleaned using 51 strokes of the head. The tiles are then immediately removed from the apparatus, rinsed under running water and patted dry using paper tissues.

As noted above, although the colouration and ease of soil removal is uniform for tiles coated with a specific fat-flour mixture, there is some variability between different batches of soil. Consequently, the results shown below in TABLE 2 are grouped in sets (TABLE 2a, 2b and 2c) , each carried out using a different batch of fat-flour soiled tiles. Experiments using Jif (TM) liquid abrasive cleaner and Domestos Multi-Surface Cleaner (TM) , a commercial hypochlorite hard surface cleaning product, are included in each series of runs to provide reference standards. The extent of soil removal is assessed visually by a panel of at least 5 people, using a standard scale. Tiles are graded on a scale ranging from 0 to 10, and panellists award integer or half- integer scores to each tile. A score of 0 denotes no visible soil removal and 10 corresponds to total soil removal. Mean scores for each soil removal system are calculated by averaging scores from both replicates. Comparing the results with conventional cleaning/bleaching systems, it can be seen that use of an oxygen transfer agent together with hydrogen peroxide provides results which are very favourably comparable with hypochlorite and commercial products based on hypochlorite, and which are significantly better than alkali and surfactant based systems. It can be seen from table 2d that while the imine quat shows a reduced effect in the presence of surfactant, the improvement over systems which do not contain the imine quat. is still measurable.

TABLE 2a

TABLE 2b

TABLE 2c

TABLE 2d

Claims

1. A bleaching composition of pH 10-14 which comprises an oxygen transfer agent and hydrogen peroxide.

2. A bleaching composition according to claim 1 wherein hydrogen peroxide is present at a level of 0.5-10%wt on product.

3. A bleaching composition according to claim 1 wherein the weight ratio of the hydrogen peroxide to the oxygen transfer agent falls in the range 5:1 to 20:1.

4. A bleaching composition according to claim 1 wherein the oxygen transfer agent is a compound comprising ions of the general structure:

(R_χ) (R₂)C=N⁺(R₃) (R₄)

wherein :

R₁ and R₄ are in a cis- relation and are substituted or unsubstituted radicals selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl and cycloalkyl radicals:

R₂ is a substituted or unsubstituted radical selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl, cycloalkyl, nito, halo, cyano, alkoxy, keto, carboxylic acid and carboalkoxy groups; and,

R₃ is a substituted or unsubstituted radical selected from the group consisting of hydrogen, phenyl, aryl, heterocyclic ring, alkyl, cycloalkyl, nito, halo and cyano groups:

5. A bleaching composition according to claim 4 wherein the oxygen transfer agent is a substituted or unsubstituted isoquinolinium salt.

6. A bleaching composition according to claim 1 having a pH of 10-12, said composition being an aqueous liquid and comprising:

a) hydrogen peroxide at a level of 0.5-10%wt on product ,

b) 0.001-10%wt on product of an isoquinolinium salt,

c) 0.01 to 30%wt on product of at least one nonionic surfactant, and,

7. A method for bleaching a stained substrate which comprises the step of treating the substrate with a bleaching composition as defined in any one of claims 1-6.