WO2005003277A1

WO2005003277A1 - Blue and red bleaching compositions

Info

Publication number: WO2005003277A1
Application number: PCT/EP2004/006242
Authority: WO
Inventors: Stephen Norman Batchelor; Sarah Dixon
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited
Priority date: 2003-06-18
Filing date: 2004-06-08
Publication date: 2005-01-13
Also published as: IN230386B; EP1633844B1; ATE391166T1; BRPI0411581A; IN2005MU01401A; EP1633844A1; ES2303076T3; DE602004012854T2; DE602004012854D1

Abstract

The present invention concerns photo-bleaching with a dye and in particular the bleaching of laundry items with a bleaching composition comprising : a) from 0.0001 to 0.1 Wt/ Wt % of a photo-reactive red dye having a peak in the visible in the range 500 to 550 nm ; b) from 0.0001 Wt/ Wt % to 0.1 Wt/ Wt of a blue dye lambda max 580-640 nm ; c) from 0 to 40 Wt/ Wt % other bleaching species; and, d) the balance carriers and adjunct ingredients to 100 Wt/ Wt % of the total bleaching composition.

Description

BLUE AND RED BLEACHING COMPOSITIONS

FIELD OF INVENTION

The present invention relates to the photo-bleaching of products, in particular laundry bleaching.

BACKGROUND OF INVENTION

In a conventional bleaching treatment, a substrate such as a laundry fabric or other textile is subjected to hydrogen peroxide, or to substances which can generate hydroperoxyl radicals, such as inorganic or organic peroxides.

A preferred approach to generating hydroperoxyl bleach radicals is the use of inorganic peroxides coupled with organic precursor compounds. These systems are employed for many commercial laundry powders. For example, various European systems are based on tetraacetyl ethylenediamine (TAED) as the organic precursor coupled with sodium perborate or sodium percarbonate, whereas in the United States laundry bleach products are typically based on sodium nonanoyloxybenzenesulphonate (SNOBS) as the organic precursor coupled with sodium perborate. Alternatively, or additionally, hydrogen peroxide and peroxy systems can be activated by bleach catalysts, such as by complexes of iron and the ligand N4Py (i.e. N, N-bis (pyridin-2-yl-methyl) - bis (pyridin-2-yl) ethylamine) disclosed in W095/34628.

Another approach to bleaching is that of using radical photo-initiators, which are generally organic chemicals which on absorption of light, particularly UV light, form reactive radicals. They are widely used to initiate the polymerisation of alkenes and thereby cure coatings. They may also be used as photobleach agents as discussed in GB 9917451. Radical photoinitiators, in general, are discussed by H.F. Gruber in Prog. Polym . Sci . Vol 1 7. 953-1044.

SUMMARY OF INVENTION

We have found that the treatment of a stained textile with a bleaching composition comprising a photo-reactive red dye having a lambda max in the visible in the range 500 to 550 nm together with a blue dye having a lambda max in the visible in the range 580 to 640 nm yields a bleached textile with enhanced whiteness. The bleaching activity is particularly good against catechol-type stains, polyphenolics-type stains and polycyclic hydroxylated aromatic-type stains.

These catechol-type stains, polyphenolics-type stains and polycyclic hydroxylated aromatic-type stains are as a result of the chromophores found in tea, coffee, blackberry, blueberry, blackcurrant, red wine, banana and the like.

These stains are. characteristic and distinct from oily food type stains such as tomato oil stain, curry oil stain, mango stain, annatto derived stain, colorau derived stain, and sebum derived stain etc.

The present invention provides a bleaching composition comprising: a) from 0.0001 to 0.1 wt/wt% of a photo-reactive red dye having a peak in the visible in the range 500 to 550 nm; b) from 0.0001 wt/wt% to 0.1 wt/wt of a blue dye lambda max 580-640 nm; c) from 0 to 40 wt/wt% other bleaching species; and, d) the balance carriers and adjunct ingredients to 100 wt/wt % of the total bleaching composition.

It is most preferred that upon addition of a unit dose of the bleaching composition to an aqueous environment a wash liquor having a pH in the range 8 to 11 is provided.

The bleaching composition may be used on its own or in conjunction with other bleaching species. It is preferred that those other bleaching species, if used, possess different bleaching profiles to the solely the photo- reactive red dye bleaching composition. The stain bleaching profile of known photo-bleaches such as radical photoinitiators, is generally that of ceretenoid type stains, for example tomato stains which is similar to the bleaching profile of ^λλair" bleaching catalysts.

Of the photo-reactive red dyes Xanthene type dyes are preferred, particularly based on the structure:

where the dye may be substituted by halogens and other elements/groups. Particularly preferred examples are Food red 14 and Rose Bengal, Phloxin B, Eosin Y. The fact that these dyes are brightly red makes their application in textile bleaching unusual because one would expect their use to result in discoloured rather than whitened textiles. When Food red 14 is used solely as the bleaching species the consumer is reassured in the laundry context that the bleach used is mild because of that fact that it is an acceptable food additive. Food dyes are used to enhance the visual appearance of many foods. As humans consume them, they undergo rigorous testing and examination to ensure they represent no risk to health.

The present invention 'also extends to a method of photo- bleaching a textile.

The light used for photo-bleaching may be sunlight, florescent light or that from an ordinary light bulb.

Photo-bleaching is still effective where the concentration of the photo-reactive red dye on the textile/cloth is so low as to be barely perceptible to the human eye. It is preferred that the dye rapidly photo-fades on irradiation with light.

The present invention may be applied locally, suitable pre- treatment means for application include sprays, pens, roller-ball devices, bars, soft solid applicator sticks.

A unit dose as used herein is a particular amount of the bleaching composition used for a type of wash. The unit dose may be in the form of a defined volume of powder, granules or tablet.

DETAILED DESCRIPTION OF THE INVENTION A photo-reactive dye is one which on exposure to light in the wavelength range 300-700nm, more preferably 400 to 700 nm, undergoes photochemical process to produce reactive/excited species that is capable of bleaching coloured stained material, such as tea stains. The photo- reaction should be able to occur in minutes to hours under normal lighting conditions (40-400 W rrf² in the 400 to 700 nm range) .

A photo-reactive red dye is one having a lambda .max in the visible in the range 500 to 550 nm, for example, Food red 14, Rose Bengal, Phloxine B, and Eosin Y.

A blue dye is one having a lambda max in the visible in the range 580 to 640 nm and may be direct or acid blue dyes such as listed by the Society of Dyers and Colourists and American Association of Textile Chemists and Colorists (see http://www.colour-index.org). Direct and acid dyes may be selected from azo, bis-azo, anthraquinone, triarylmethane dyes. Preferred dyes are clearly those that deposit on cotton. Preferred direct and acid dyes are those that deposit on cotton but do not build up on cotton. over multiple washes, examples of dyes that do not build up are acid black 1, acid blue 29, acid blue 113, and acid black 24. Particularly preferred are dyes, which deposit on cotton but do not deposit on nylon, such as acid black 1 and acid blue 29. The blue dye also serves to mask any residual red colour, the combination or red and blue providing a violet colour that enhances the whiteness of the fabric.

The preferred photo-reactive red dye is Food red 14 (Erythrosine B) (E 127; CI number 45430) (CAS 16423-68-0) which is a widely used red food colouring, see Hunger K. Industrial Dyes: Chemistry Properties And Applications. Wiley-VCH, Heidelberg 2003.

The concentration of the photo-reactive red dye -in a wash liquor is from 5ppb to lOOOppm, preferably lOppb to lOOppm, more preferably 50ppb to 5ppm, and most preferably lOOppb to lppm. A same concentration may also be used for a spot treatment of a stain or of a commercial liquid formulation. A suitable concentration in a powder detergent would be 0.0001 wt/wt% to 0.1 wt/wt%, most preferred is 0.001 wt/wt% to 0.01 wt/wt%.

A dye in the context of the current invention is described as an organic compound with an optical absorption maximum in the visible wavelength range of 400-700nm, such that the extinction coefficient at the maximum in the visible is greater than 5000 mol/l/cm, most preferably grater than 10000 mol/l/cm.

The use of a blue dye to give shading is described in co- pending GB application 0314211.4 filed on 18/6/2003. In this manner, yellowing of whites may be reduced and an aesthetically pleasing blue hue given to the wash liquor. It is preferred that the red dye:blue dye is in the ratio 9:1 to 1:9.

The concentration of the blue dye in a wash liquor is from 5ppb to lOOOppm, preferably lOppb to lOOppm, more preferably 50ppb to 5ppm, and most preferably lOOppb to lppm. A same concentration may also be used for a spot treatment of a stain or of a commercial liquid formulation. A suitable concentration in a powder detergent would be 0.0001 wt/wt% to 0.1 wt/wt%, most preferred is 0.001 wt/wt% to 0.01 wt/wt% .

Of the blue dyes cotton substantive dyes are preferred over cotton non-substantive dyes. In this regards, a cotton substantive dye is defined as in co-pending GB application 0314211.4.

Other Bleaching Species

The bleaching composition may also contain other bleaching components, for example other photo-bleaches, a transition metal catalyst which is present in a bleaching composition that is substantially devoid of peroxyl species, and peroxyl bleaching systems. An example of a preferred additional photo-bleach is vitamin K3.

The use of bleaching catalysts for stain removal has been developed over recent years and may be used in the present invention. Examples of transition metal catalysts that may be used are found, for example, in: WO0060045, WO0248310, WO0029537 and WO0012667. The catalysts may be used for catalysing peroxyl or "air" bleaching as described in WO0248301. The catalyst may alternatively be provided as the free ligand that forms a complex in situ.

The bleaching composition when use as an "air" bleaching composition is substantially devoid of a peroxygen bleach or a peroxy-based or peroxyl-generating bleach system. It is believed that adventitious hydroperoxides within an oily stain serve to bleach the stain together with the catalyst. The term "substantially devoid of a peroxygen bleach or a peroxy-based or peroxyl-generating bleach system" should be construed within spirit of the invention. It is preferred that the composition has as low a content of peroxyl species present as possible. It is preferred that the bleaching formulation contains less that 1 % wt/wt total concentration of peracid or hydrogen peroxide or source thereof, preferably the bleaching formulation contains less that 0.3 % wt/wt total concentration of peracid or hydrogen peroxide or source thereof, most preferably the bleaching composition is devoid of peracid or hydrogen peroxide or source thereof.

In contrast to air bleaching a peroxyl species is required. The peroxy bleaching species may be a compound, which is capable of yielding hydrogen peroxide in aqueous solution. Hydrogen peroxide sources are well known in the art. They include the alkali metal peroxides, organic peroxides such as urea peroxide, and inorganic persalts, such as the alkali metal perborates, percarbonates, perphosphates persilicates and persulphates. Mixtures of two or more such compounds may also be suitable.

Particularly preferred are sodium perborate tetrahydrate and, especially, sodium perborate monohydrate. Sodium perborate monohydrate is preferred because of its high active oxygen content. Sodium percarbonate may also be preferred for environmental reasons. The amount thereof in the composition of the invention usually will be within the range of about 1-35% by weight, preferably from 5-25% by weight. One skilled in the art will appreciate that these amounts may be reduced in the presence of a bleach precursor e.g., N,N,N'N' -tetraacetyl ethylene diamine (TAED) .

Another suitable hydrogen peroxide generating system is a combination of a C1-C4 alkanol oxidase and a C1-C4 alkanol, especially a combination of methanol oxidase (MOX) and ethanol . Such combinations are disclosed in International Application PCT/EP 94/03003 (Unilever), which is incorporated herein by reference.

Alkylhydroxy peroxides are another class of peroxy bleaching compounds. Examples of these materials include cumene hydroperoxide and t-butyl hydroperoxide.

Organic peroxyacids may also be suitable as the peroxy bleaching compound. Such materials normally have the general formula:

wherein R is an alkylene or substituted alkylene group containing from 1 to about 20 carbon atoms, optionally having an internal amide linkage; or a phenylene or substituted phenylene group; and Y is hydrogen, halogen, alkyl, aryl, an imido-aromatic or non-aromatic group, a COOH or

group or a quaternary ammonium group.

Typical monoperoxy acids useful herein include, for example: (i) peroxybenzoic acid and ring-substituted peroxybenzoic acids, e.g. peroxy-alpha-naphthoic acid;

(ii) aliphatic, substituted aliphatic and arylalkyl monoperoxyacids, e.g., peroxylauric acid, peroxystearic acid and N,N-phthaloylaminoperoxy caproic acid (PAP); and

(iii) 6-octylamino-6-oxo-peroxyhexanoic acid.

Typical diperoxyacids useful herein include, for example:

(iv) 1, 12-diperoxydodecanedioic acid (DPDA) ;

(v) 1, 9-diperoxyazelaic acid; (vi) diperoxybrassilic acid; diperoxysebasic acid and diperoxyisophthalic acid;

(vii) 2-decyldiperoxybutane-l, 4-diotic acid; and (viii) 4, 4 ' -sulphonylbisperoxybenzoic acid.

Also inorganic peroxyacid compounds are suitable, such as for example potassium monopersulphate (MPS) . If organic or inorganic peroxyacids are used as the peroxygen compound, the amount thereof will normally be within the range of about 2-10% by weight, preferably from 4-8% by weight. Peroxyacid bleach precursors are known and amply described in literature, such as in the British Patents 836988; 864,798; 907,356; 1,003,310 and 1,519,351; German Patent 3,337,921; EP-A-0185522; EP-A-0174132; EP-A-0120591; and U.S. Pat. Nos. 1,246,339; 3,332,882; 4,128,494; 4,412,934 and 4,675,393.

Another useful class of peroxyacid bleach precursors is that of the cationic i.e. quaternary ammonium substituted peroxyacid precursors as disclosed in US Pat. Nos. 4,751,015 and 4,397,757, in EP-A0284292 and EP-A-331, 229. Examples of peroxyacid bleach precursors of this class are:

2- (N,N,N-trimethyl ammonium) ethyl sodium-4-sulphonphenyl carbonate chloride (SPCC) ;

N-octyl-N,N-dimethyl-N10-carbophenoxy decyl ammonium chloride (ODC) ;

3- (N,N,N-trimethyl ammonium) propyl sodium-4-sulphophenyl carboxylate; and

N,N,N-trimethyl ammonium toluyloxy benzene sulphonate.

A further special class of bleach precursors is formed by the cationic nitriles as disclosed in EP-A-303,520 and in European Patent Specification No.'s 458,396 and 464,880.

Any one of these peroxyacid bleach precursors can be used in the present invention, though some may be more preferred than others. Of the above classes of bleach precursors, the preferred classes are the esters, including acyl phenol sulphonates and acyl alkyl phenol sulphonates; the acyl-amides; and the quaternary ammonium substituted peroxyacid precursors including the cationic nitriles.

Examples of said preferred peroxyacid bleach precursors or activators are sodium-4-benzoyloxy benzene sulphonate (SBOBS) ; N,N,N'N'-tetraacetyl ethylene diamine (TAED) ; sodium-l-methyl-2-benzoyloxy benzene-4-sulphonate; sodium-4- methyl-3-benzoloxy benzoate; SPCC; trimethyl ammonium toluyloxy-benzene sulphonate; sodium nonanoyloxybenzene sulphonate (SNOBS); sodium 3, 5, 5-trimethyl hexanoyl- oxybenzene sulphonate (STHOBS) ; and the substituted cationic nitriles.

Other classes of bleach precursors for use with the present invention are found in WO0015750, for example 6- (nonanamidocaproyl) oxybenzene sulphonate .

The precursors may be used in an amount of up to 12%, preferably from 2-10% by weight, of the composition.

Balance Carriers and Adjunct Ingredients The following provides examples of suitable balance carriers and adjunct ingredients.

These are generally surfactants, builders, foam agents, anti-foam agents, solvents, and enzymes. The use and amounts of these components are such that the bleaching composition performs depending upon economics, environmental factors and use of the bleaching composition. It is preferred that the bleaching composition comprises from 5 to 40 wt/wt % of a surfactant having an HLB greater than 15.

To that extent, the composition comprises a surfactant and optionally other conventional detergent ingredients. The invention in its second aspect provides an enzymatic detergent composition which comprises from 0.1 - 50 % by weight, based on the total detergent composition, of one or more surfactants. This surfactant system may in turn comprise 0 - 95 % by weight of one or more anionic surfactants and 5 to 100 % by weight of one or more nonionic surfactants. The surfactant system may additionally contain amphoteric or zwitterionic detergent compounds, but this in not normally desired owing to their relatively high cost. The enzymatic detergent composition according to the invention will generally be used as a dilution in water of about 0.05 to 2%.

In general, the nonionic and anionic surfactants of the surfactant system may be chosen from the surfactants described "Surface Active Agents" Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, in the current edition of "McCutcheon¹ s Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981. Suitable nonionic detergent compounds which may be used include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic detergent compounds are C₆-C₂₂ alkyl phenol-ethylene oxide condensates, generally 5 to 25 EO, i.e. 5 to 25 units of ethylene oxide per molecule, and the condensation products of aliphatic C₈- Ci₈ primary or secondary linear or branched alcohols with ethylene oxide, generally 5 to 40 EO.

Suitable anionic detergent compounds which may be used are usually water-soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher Cβ-Ciβ alcohols, produced for example from tallow or coconut oil, sodium and potassium alkyl Cg-C₂o benzene sulphonates, particularly sodium linear secondary alkyl C₁₀-C₁₅ benzene sulphonates; and sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum. The preferred anionic detergent compounds are sodium Cn-Cι₅ alkyl benzene sulphonates and sodium Cι₂-Cι₈ alkyl sulphates. Also applicable are surfactants such as those described in EP-A-328 177 (Unilever) , which show resistance to salting-out, the alkyl polyglycoside surfactants described in EP-A-070 074, and alkyl monoglycosides .

Preferred surfactant systems are mixtures of anionic with nonionic detergent active materials, in particular the groups and examples of anionic and nonionic surfactants pointed out in EP-A-346 995 (Unilever) . Especially preferred is surfactant system that is a mixture of an alkali metal salt of a Ci6~Ci8 primary alcohol sulphate together with a Cι₂-Ci5 primary alcohol 3-7 EO ethoxylate.

The nonionic detergent is preferably present in amounts greater than 10%, e.g. 25-90% by weight of the surfactant system. Anionic surfactants can be present for example in amounts in the range from about 5% to about 40% by weight of the surfactant system.

The composition may contain additional enzymes as found in WO 01/00768 Al page 15, line 25 to page 19, line 29, the contents of which are herein incorporated by reference.

Builders, polymers and other enzymes as optional ingredients may also be present as found in WO0060045.

Suitable detergency builders as optional ingredients may also be present as found in WO0034427.

The composition of the present invention may be used for laundry cleaning, hard surface cleaning (including cleaning of lavatories, kitchen work surfaces, floors, mechanical ware washing etc.) . As is generally known in the art, bleaching compositions are also employed in waste-water treatment, pulp bleaching during the manufacture of paper, leather manufacture, dye transfer inhibition, food processing, starch bleaching, sterilisation, whitening in oral hygiene preparations and/or contact lens disinfection. In the context of the present invention, bleaching should be understood as relating generally to the decolourisation of stains or of other materials attached to or associated with a substrate. However, it is envisaged that the present invention can be applied where a requirement is the removal and/or neutralisation by an oxidative bleaching reaction of malodours or other undesirable components attached to or otherwise associated with a substrate.

Examples

Example 1

A 1.5g/L stock solution of a base washing powder was created. The washing powder contained 18% NaLAS, 73% salts

(silicate, sodium tripolyphosphate, sulphate, carbonate) , 3% minors including perborate, fluoreser and enzymes, remainder impurities and water. The solution was divided into 4, 200ml aliquots. To each was added various amounts of the food red 14, and then 2 BC1 test clothes and 4 white cotton clothes. All clothes were the same size and weight, the total weight of cloth added was 5g. BC1 is a standard stained test cloth used in laundry evaluation and is a model tea stain monitor. BC1 clothes may be purchased from e.g., the center for test materials, Vlaardingen, NL.

The clothes were then agitated in solution for 20 mins, removed rinsed and the 2 BC1 clothes and 2 of the white clothes irradiated in a weatherometer (WOM) for 30 minutes. A WOM produces artificial sunlight and was set up to give 385 W/m² in the UV-visible range. The remaining 2 white clothes were dried in the dark in a tumble drier.

Following these procedures the colour of the clothes were measured using a reflectance spectrometer and expressed as the ΔE relative to washed clean white cloth. The results are presented in the table below

Clear photo-bleaching of the BCl stain is observed. A small amount of red colouration is transferred to the white cloth. This red colouration is removed by exposure to sunlight.

Example 2

A lg/L SDS surfactant stock solution in water was created. The solution was divided in two and the two halves, and buffered to pH 10 and pH 8 respectively using standard salts (Hydrion ™ buffer, purchased from Sig a-Aldrich) . The solution was used to wash BCl stains as follows. A 3.7g piece of BCl stained cotton cloth plus a 0.7g piece of clean white woven cotton cloth were agitated in 100ml of wash solution for 20 mins, rinsed twice, then the BCl cloth irradiated in a WOM for thirty minutes. The ΔE of the clothes relative to a clean standard was then measured. The clothes were then irradiated for a further 30 minutes and remeasured.

The experiment was repeated using wash solution containing different amounts of Food red 14. The optical density (5cm) of the wash solutions were measured at the lambda (max) of the dye (527nm)

All the white clothes were tumbled dried in the dark and the pick up of red dye measured by measuring the ΔE of the clothes relative to a clean undyed standard.

The results are reported in the table below:

Table

^•''average of 4 independent measurements ²average of 2 independent measurements

Photobleaching of the BCl stain was observed from all solution containing food red 14. Notably this occurs even at extremely low levels of the dye, 0. lppm, at this level the dye is barely visible in solution and no red colour could be discerned by eye on the white cloth. However the BCl cloth was visibly bleached. The red colour on the white cloth was removed simply by leaving in natural light.

Example 3

Stains were created on white woven cotton by: placing 1 drop of (a) a saturated solution of turmeric in soya oil or (b) placing 2 drop of Brazilian palm oil.

Three of each type of stains (a) , (b) , BCl stains and four clean white ballast pieces (total weight =11.4g) were wash at 40°C for 20 minutes in 200 ml of water containing 7g/L of Persil Colour™ washing powder. Persil Colour™ contains less than 5% soap. Polycarboxylate and phosphonate, 5 to 15% anionic and non-ionic surfactants, 15-30% zeolite and also contains enzymes. Following the wash the cloths were rinsed once in water, once in an acidic solution, and finally once more in water. They were then all irradiated in a WOM for 36 minutes. The residual staining and relative to clean white cloth measured using a reflectometer and expressed as the ΔE value. The discoloration of the white ballast due to transfer of coloured stain matter in the wash was measured in an analogous manner.

The experiment was repeated but with the following, added to the wash solution: (a) 1 ppm food red 14 (b) 10 ppm vitamin K3 (a radical photo-initiator which bleaches carotenoid stains) (c) 1 ppm food red 14 plus 10 ppm vitamin K3

The results are displayed in the table below

Table

The combination of the Food red 14 with the vitamin K3 gives good overall bleach effects.

Example 4

A 3.7g piece of BCl stained cotton cloth was washed in 80ml of a pH=10 buffered solution of 0.2g/L SDS. The wash consisted in a 15 minute agitation followed by rinsing. The cloth was then irradiated in a WOM for 30 minutes and the residual staining measured as the ΔE relative to clean white cotton. The experiment was also performed with wash liquors containing various xanthene type dyes. The % deposition of the dyes onto the cloth was obtained by measuring the UV-VI spectrum of the wash liquors before and after washing. The results are shown in the table below.

Table

^xaverage of 4 independent measurements

From the results Food red 14 and Rose Bengal provide superior bleaching.

Example 5

A stock solution of 1.5g/L of a base washing powder in water was created. The washing powder contained 18% NaLAS, 73% salts (silicate, sodium tri-poly-phosphate, sulphate, carbonate) , 3% minors including perborate, fluorescer and enzymes, remainder impurities and water. The solution was divided into 60ml aliquots and various combination of food red 14 dye with acid blue 29 added to this in amount as indicated in the results table. 1 piece of bleached, non- mercerised, non-fluorscent woven cotton cloth (ex Phoenic Calico) weighing 1.3g was placed in the solution at room temperature (20°C) . This cloth represents a slightly yellow cotton. The cloth was left to soak for 45 minutes then the solution agitated for 10 mins, rinsed and dried in the dark. After the washes the Ganz whiteness of the cloth was measured (see "assessment of Whiteness and Tint of Fluorescent Substrates with Good Interinstrument Correlation" Colour Research and Applica tion 19, 1994) . A higher value of Ganz is associated with whiter cloth. The results are the average of 2 experiments.

Table

Mixture of food red 14 with the blue dyes gives an increase in the whiteness of the cloth. The dye acid black 1 gave similar results.

Example 6

The experiment of example 5 was repeated. Except here one 3.7g piece of BCl stained cotton cloth was washed in 60 ml of solution containing various amounts of food red 14 and acid blue 29. The wash consisted of 30 minutes of agitation. Following the rinses the clothes were irradiated in a WOM for 30 minutes and the residual stain measured as the ΔE relative to clean white cloth. The results are shown in the table below.

Table

¹average of 4 independent measurements.

Hence the mixture of dyes gives photo-bleach effects and shading benefit (example 5) .

Example 7

A solution of 0.2g/L SDS surfactant was created in pH=10 buffer (Hydrion ™) . The solution was divided in 2 and RoseBengal added to one half such that its Optical density at the maximum absorption of the dye in the visible was 0.81 (5cm) . A similar solution was created for Food Red 14 but with a higher optical density of 0.93. The Solution of Food Red 14 under indoor lighting was much paler to the eye than that of Rose Bengal. This was confirmed by 12 independent adults aged in the range 25-60 years. All stated the Rose Bengal solution to have a more intense colour, despite the fact it had a lower optical density. This clearly shows the advantage in being able to dose Food red 14 at a higher level without over colouring the liquor.

Claims

We claim:

1. A bleaching composition comprising: a) from 0.0001 to 0.1 wt/wt% of a photo-reactive red dye having a peak in the visible in the range 500 to 550 nm; b) from 0.0001 wt/wt% to 0.1 wt/wt of a blue dye lambda max 580-640 nm; c) from 0 to 40 wt/wt% other bleaching species; and, d) the balance carriers and adjunct ingredients to 100 wt/wt % of the total bleaching composition.

2. A bleaching composition according to claim 1, wherein the photo-reactive red dye is a xanthene dye.

A bleaching composition according to claim 2, wherein photo-reactive red dye is selected from the group consisting of Eosin Y, Phloxine B, Rose Bengal, and Food Red 14.

A bleaching composition according to claim 3, wherein the photo-reactive red dye is Food red 14.

5. A bleaching composition according to any preceding claim, wherein the blue dye is selected from the group consisting of: acid blue dyes and direct blue dyes.

6. A bleaching composition according to claim 5, wherein the blue dye is an acid blue dye selected from the group consisting of: acid black 1, acid blue 29, acid blue 113, and acid black 24.

7. A bleaching composition according to any preceding claim, wherein the photo-reactive red dye:blue dye is in the ratio 9:1 to 1:9.

8. A bleaching composition according to any preceding claim, wherein the bleaching composition comprises other photo-bleaches .

9. A bleaching composition according to claim 8, wherein the bleaching composition comprises vitamin K3.

10. A bleaching composition according to any preceding claim, wherein the bleaching composition comprises a peroxyl species .

11. A bleaching composition according to claim 10, wherein the bleaching composition comprises a bleach activator.

12. A bleaching composition according to any one of claims 1 to 9, wherein the bleaching composition comprises an air bleach catalyst or ligand thereof, the bleaching composition comprising less than 1 % wt/wt total concentration peroxy-based or peroxyl-generating bleach system.

13. A bleaching composition according to claim 1 to 9 and 12, wherein the bleaching composition is a liquid bleaching composition.

14. A bleaching composition according to any preceding claim, wherein the bleaching composition comprises from 5 to 40 wt/wt % of a surfactant having an HLB greater than 15.