WO2010034623A1

WO2010034623A1 - Cationic pyridine and pyridazine dyes

Info

Publication number: WO2010034623A1
Application number: PCT/EP2009/061761
Authority: WO
Inventors: Stephen Norman Batchelor; Jayne Michelle Bird; Susan Barbara Joyce
Original assignee: Unilever Plc; Unilever N.V.; Hindustan Unilever Limited
Priority date: 2008-09-23
Filing date: 2009-09-10
Publication date: 2010-04-01
Also published as: EP2331669A1; ZA201101402B; EP2331669B1; CL2011000620A1; MY153959A; ES2450393T3; CN102159698A; CN102159698B; AR073649A1

Abstract

The present invention provides a laundry detergent comprising a cationic pyridine/pyridazine dye. The present invention also provides a method of treating a textile.

Description

CATIONIC PYRIDINE AND PYRIDAZINE DYES

Field of Invention

The present invention relates to the delivery of dyes to fabrics.

Background of the Invention

Many garments yellow over multiple wash wear cycles, reducing the aesthetic value of the garment. In order to maintain the white appearance shading dyes may be used. For main wash applications these are preferably violet dyes. Typically direct violet dyes, such as direct violet 9 or 99 have been used and these dyes are described in WO2005014769 and WO2005003274. Direct dyes build up over multiple washes, and this can lead to a strong blue or violet colour on the garment. To make this overshading acceptable lower level of dye must be used, reducing the benefit.

WO 2007/084729, to Proctor and Gamble, discloses the use of thiazolium dyes in Laundry formulations as a shading agent that does not build up over multiple washes.

WO 2007/087252, to Milliken, discloses the use of thiazolium dyes in Laundry formulations as a shading agent that does not build up over multiple washes.

GB1491930, to L'Oreal, discloses cationic pyridine based mono-azo dyestuffs in composition for hair dyeing. Summary of the Invention

We have found that cationic blue and violet N-heterocyclic mono-azo dyes of the current invention give better performance in laundry applications over those disclosed in WO 2007/084729 and WO 2007/087252.

In one aspect the present invention provides a laundry treatment composition comprising:

(i) from 2 to 70 wt% of a surfactant, from 0.005 to 2 wt %, of a fluorescer, and from 0.0001 to 0.1 wt% of a blue or violet cationic pyhdine/pyhdazine dye of the following structure:

wherein

X is selected from: N; CH; and, C-N=N-phenyl(B)-para-NR1 R2;

Ri and R₂ are independently selected from H, alkyl, aryl; alkylaryl; alkylesters; polyethers; and Ri and R2 may be joined to form a five or six member aliphatic ring which may comprise a further hetroatom selected from oxygen and nitrogen;

R₃ is selected from: H; alkyl; alkylaryl; and, aryl; and,

Ring A may be further condensed to a benzene ring. The C-N=N-phenyl(B)-para-NR1 R2 group as given indicates ortho substitution of the azo group to the quaternary nitrogen in the structure.

In another the present invention provides a domestic method of treating a textile, the method comprising the steps of: (i) treating a textile with an aqueous solution of the cationic pyhdine/pyhdazine dye, the aqueous solution comprising from 1 ppb to 1 ppm of the cationic pyridine/pyhdazine dye, and from 0 ppb to 1 ppm of another dye or pigment selected from: pigments, hydrophobic dyes and direct dyes; and, from 0.0 g/L to 3 g/L of a surfactant; (ii) optionally rinsing the textile; and, (iii) drying the textile. Preferably, the aqueous solution comprises 0.1 to 50 ppm of fluorescer.

Preferably the textile to be laundered is composed of cotton, polyester, nylon or elastane fibres.

Detailed Description of the Invention

The cationic pyridine/pyhdazine dyes as used in the present invention are blue or violet. In this regard, the cationic pyridine/pyhdazine dyes gives a blue or violet colour to a white cloth with a hue angle of 240 to 345, more preferably 260 to 320, most preferably 270 to 300. The white cloth used is bleached non-mercerised woven cotton sheeting.

The aromatic rings and Ri, R2 and R3 of the dye may be further substituted by suitable uncharged organic groups. The suitable uncharged organic groups individually should have a molecular weight of less than 400, preferably less than 150. The uncharged organic group should contain less than or equal to 3 carbon- carbon double bonds (C=C), most preferably no carbon-carbon double bonds. Preferably the uncharged organic groups are selected from methyl, ethyl, - A -

NHCOCH₃, CH₃O, C₂H₅O, HO, amine, Cl, F, Br, I, NO₂, CH₃SO₂, C₂H₅SO₂, CN, CONH₂. Preferably, any aromatic ring in the cationic pyridine/pyridazine dye is not substituted directly by OH, i.e., a phenolic moiety should not be present.

A polyether chain (polyether) is defined as at least two repeating units that are chemically bound via the ether's oxygen. The polyether chain may be branched or linear. Preferred polyether chains are selected from ethylene oxides or propylene oxides. Where an alkyl and/or polyether chain is present the chain preferably has a molecular weight of less than 1000, more preferably less than 400, even more preferably less than 200. Preferably R1 and/or R2 is a polyether chain as defined above.

Example of polyether groups are (CH₂CH₂O)₄H₁(CH₂CH₂CH₂O)₃H, (CH₂C(CH₃)HO)₃H, (CH₂CH₂O)₂(CH₂C(CH₂O(CH₂CH₂O)₂H)₂H and those described in WO2008/087497.

An- is a counter ion. An- is not essential aspect of the invention and may be varied widely. An- may be an anion such as RCOO^", BPh₄ ^", CIO₄ ^", BF₄ ^", PF₆ ^", RSO₃ ^", RSO₄ ^", SO₄ ^2", NO₃ ^", F^", Cl^", Br^", or I^", with R being hydrogen, optionally substituted alkyl or optionally substituted aryl. Preferably An- is selected from: CH₃SO₃ ^" , CH₃CO₂ ^", BF₄ ^", Cl^", F^", Br^", and I^".

When Ri and R₂ are joined to form an aliphatic ring it is preferred that the aliphatic ring is a morpholine or pipehdine ring.

The azo group is preferably ortho to the quanternary nitrogen.

When A is further condensed to a benzene ring, the A ring forms an extended aromatic ring system of the form: or

or

Most preferably, Ri and R2 are selected from: H; polyethers, C1 -C8-alkyl which may be substituted by -OH, O-C1 -C8-alkyl, -Cl, and -F, -CN; -C1 -C8-alkyl-C(O)2- C1 -C8-alkyl; -C1 -C8-alkyl-OC(O)-C1 -C8-alkyl;-C1 -C8-alkyl-phenyl; -C1 -C8-alkyl- naphthyl; phenyl; and, naphthyl, wherein the benzyl and phenyl may be substituted by a group selected from: -OC1 -C6-alkyl, -C1-C6-alkyl. More preferably, Ri and R₂ are selected from: -H; -CH₃; -C₂H₅; -(CH₂)₃H; -(CH₂)₄H; - C₂H₄OH; -C₂H₄CI; -C₂H₄CN; -C₆H₅; -CH₂C₆H₅; -C₂H₄OCOCH₃; -C₂H₄COOCH₃; and, -C₂H₄OC₂H₄OH. Most preferred groups for Ri and R₂ are methyl or ethyl.

Preferably, R₃ is selected from: H, C1 -C8-alkyl, -d -Cβ-alkyl-phenyl; -C1 -C8-alkyl- naphthyl; phenyl; and, naphthyl. More preferably, R₃ is selected from methyl, ethyl and benzyl. Most preferred groups for R₃ are methyl or ethyl.

Ring B may carry up to two groups that are selected from: -Br; -Cl; -F; -NO₂; -CN; -SO2-benzyl; -C(O)O-CI -C8-alkyl; -OC1 -C8-alkyl; -NHC(O)CI -C4-alkyl, -SO2-C1 - C8-alkyl; and -SO2-phenyl. More preferably -Br; -Cl; -F; -OC1-C4-alkyl and - NHC(O)CI -C4-alkyl. When the B ring is further substituted this is preferably ortho and/or meta to the -NRiR₂ amine group. If substituted by 2 groups, one is preferably ortho and the other meta to the -NRiR₂ amine group and on opposite sides of the ring (i.e. in the 2, 5 positions). The most preferred substituents for the B ring are selected from methyl, Cl, NHCOCH₃, CH₃O and C₂H₅O.

Deposition of the dye onto polyester may be increased by increasing the number of hydrophobic organic groups on the dye. Hydrophobic organic groups are groups which increase the calculate logP of the dye in comparison to a H substituent.

Example compounds that are preferred:

Synthesis of these compounds is well discussed in the literature, US3117116 (Hoechst), US2864813 (Geigy), US3562245 (Hoechst) and US3510488 (Kuhlmann).

For inclusion in alkaline detergent powders it is preferred if the dyes are granulated with an acidic binder as described in WO2007/039042 (Unilever). This reduced degradation due to alkaline hydrolysis on storage.

Surfactant

The composition comprises between 2 to 70 wt% of a surfactant, most preferably 10 to 30 wt %. 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, lnterscience 1949, Vol. 2 by Schwartz, Perry & Berch, lnterscience 1958, in the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981. Preferably the surfactants used are saturated. 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 Cβ to 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 to 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 C₈ to Ci₈ alcohols, produced for example from tallow or coconut oil, sodium and potassium alkyl Cg to C20 benzene sulphonates, particularly sodium linear secondary alkyl C10 to 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 Cu to C15 alkyl benzene sulphonates and sodium C12 to Ci₈ 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 C16 to Ciβ primary alcohol sulphate together with a C12 to C15 primary alcohol 3 to 7 EO ethoxylate.

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

In another aspect which is also preferred the surfactant may be a cationic such that the formulation is a fabric conditioner.

Cationic Compound

When the present invention is used as a fabric conditioner it needs to contain a cationic compound.

Most preferred are quaternary ammonium compounds.

It is advantageous if the quaternary ammonium compound is a quaternary ammonium compound having at least one C12 to C22 alkyl chain.

It is preferred if the quaternary ammonium compound has the following formula:

R2

I ₊

R1 -N-R3 X I R4

in which R¹ is a C12 to C22 alkyl or alkenyl chain; R², R³ and R⁴ are independently selected from Ci to C₄ alkyl chains and X^" is a compatible anion. A preferred compound of this type is the quaternary ammonium compound cetyl thmethyl quaternary ammonium bromide.

A second class of materials for use with the present invention are the quaternary ammonium of the above structure in which R¹ and R² are independently selected from Ci2 to C22 alkyl or alkenyl chain; R³ and R⁴ are independently selected from Ci to C₄ alkyl chains and X^" is a compatible anion.

A detergent composition according to claim 1 in which the ratio of (ii) cationic material to (iv) anionic surfactant is at least 2:1.

Other suitable quaternary ammonium compounds are disclosed in EP 0 239 910 (Proctor and Gamble).

It is preferred if the ratio of cationic to nonionic surfactant is from 1 :100 to 50:50, more preferably 1 :50 to 20:50.

The cationic compound may be present from 1.5 wt % to 50 wt % of the total weight of the composition. Preferably the cationic compound may be present from 2 wt % to 25 wt %, a more preferred composition range is from 5 wt % to 20 wt %.

The softening material is preferably present in an amount of from 2 to 60% by weight of the total composition, more preferably from 2 to 40%, most preferably from 3 to 30% by weight.

The composition optionally comprises a silicone. Builders or Complexing agents:

Builder materials may be selected from 1 ) calcium sequestrant materials, 2) precipitating materials, 3) calcium ion-exchange materials and 4) mixtures thereof.

Examples of calcium sequestrant builder materials include alkali metal polyphosphates, such as sodium tripolyphosphate and organic sequestrants, such as ethylene diamine tetra-acetic acid.

Examples of precipitating builder materials include sodium orthophosphate and sodium carbonate. Preferably, the laundry treatment composition comprises sodium carbonate in the range from 5 to 50 wt%, most preferably 10 to 35 wt%. In the method, when used with granular laundry treatment composition, the aqueous wash solution preferably comprises 0.1 to 4 g/L of sodium carbonate.

Examples of calcium ion-exchange builder materials include the various types of water-insoluble crystalline or amorphous aluminosilicates, of which zeolites are the best known representatives, e.g. zeolite A, zeolite B (also known as zeolite P), zeolite C, zeolite X, zeolite Y and also the zeolite P-type as described in EP-A-0,384,070.

The composition may also contain 0-65 % of a builder or complexing agent such as ethylenediaminetetraacetic acid, diethylenetriamine-pentaacetic acid, alkyl- or alkenylsuccinic acid, nithlotriacetic acid or the other builders mentioned below. Many builders are also bleach-stabilising agents by virtue of their ability to complex metal ions.

Zeolite and carbonate (carbonate (including bicarbonate and sesquicarbonate) are preferred builders. The composition may contain as builder a crystalline aluminosilicate, preferably an alkali metal aluminosilicate, more preferably a sodium aluminosilicate. This is typically present at a level of less than 15%w. Aluminosilicates are materials having the general formula:

0.8-1 .5 M₂O. AI₂O₃. 0.8-6 SiO₂

where M is a monovalent cation, preferably sodium. These materials contain some bound water and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates contain 1.5-3.5 SiO₂ units in the formula above. They can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature. The ratio of surfactants to alumuminosilicate (where present) is preferably greater than 5:2, more preferably greater than 3:1.

Alternatively, or additionally to the aluminosilicate builders, phosphate builders may be used. In this art the term 'phosphate' embraces diphosphate, triphosphate, and phosphonate species. Other forms of builder include silicates, such as soluble silicates, metasilicates, layered silicates (e.g. SKS-6 from Hoechst).

Preferably the laundry detergent formulation is a non-phosphate built laundry detergent formulation, i.e., contains less than 1 wt% of phosphate.

Enzymes

The composition may comprise one or more enzymes, which provide cleaning performance, fabric care and/or sanitation benefits. Fluorescent Agent

The composition preferably comprises a fluorescent agent (optical bhghtener). Fluorescent agents are well known and many such fluorescent agents are available commercially. Usually, these fluorescent agents are supplied and used in the form of their alkali metal salts, for example, the sodium salts. The total amount of the fluorescent agent or agents used in the composition is generally from 0.005 to 2 wt %, more preferably 0.01 to 0.1 wt %. Preferred classes of fluorescer are: Di-styryl biphenyl compounds, e.g. Tinopal (Trade Mark) CBS-X, Di-amine stilbene di-sulphonic acid compounds, e.g. Tinopal DMS pure Xtra and Blankophor (Trade Mark) HRH, and Pyrazoline compounds, e.g. Blankophor SN. Preferred fluorescers are: sodium 2 (4-styryl-3-sulfophenyl)-2H-napthol[1 ,2- d]thazole, disodium 4,4'-bis{[(4-anilino-6-(N methyl-N-2 hydroxyethyl) amino 1 ,3,5- thazin-2-yl)]amino}stilbene-2-2' disulfonate, disodium 4,4'-bis{[(4-anilino-6- morpholino-1 ,3,5-thazin-2-yl)]amino} stilbene-2-2' disulfonate, and disodium 4,4'- bis(2-sulfostyryl)biphenyl.

Perfume

Preferably the composition comprises a perfume. The perfume is preferably in the range from 0.001 to 3 wt %, most preferably 0.1 to 1 wt %. Many suitable examples of perfumes are provided in the CTFA (Cosmetic, Toiletry and Fragrance Association) 1992 International Buyers Guide, published by CFTA Publications and OPD 1993 Chemicals Buyers Directory 80th Annual Edition, published by Schnell Publishing Co.

It is commonplace for a plurality of perfume components to be present in a formulation. In the compositions of the present invention it is envisaged that there will be four or more, preferably five or more, more preferably six or more or even seven or more different perfume components. In perfume mixtures preferably 15 to 25 wt% are top notes. Top notes are defined by Poucher (Journal of the Society of Cosmetic Chemists 6(2):80 [1955]). Preferred top-notes are selected from citrus oils, linalool, linalyl acetate, lavender, dihydromyrcenol, rose oxide and cis-3-hexanol.

Perfume and top note may be used to cue the whiteness benefit of the invention.

It is preferred that the laundry treatment composition does not contain a peroxygen bleach, e.g., sodium percarbonate, sodium perborate, and peracid.

Polymers

The composition may comprise one or more polymers. Examples are carboxymethylcellulose, poly (ethylene glycol), polyvinyl alcohol), polycarboxylates such as polyacrylates, maleic/acrylic acid copolymers and lauryl methacrylate/acrylic acid copolymers.

Polymers present to prevent dye deposition, for example poly(vinylpyrrolidone), poly(vinylpyridine-N-oxide), and poly(vinylimidazole), are preferably absent from the formulation.

Experimental

Example 1

SYNTHESIS OF 1 ,5-DIMETHYL-2-r(4-DIMETHYLAMINO)-PHENYLAZO1- PYRIDINIUM IODIDE

(i) Preparation of disperse dye, 5-methyl-2-[(4-dimethylamino)-phenylazo]- pyridine 2-Amino-5-picoline (2.16g) and sodamide (50%w/w suspension in toluene, 1.56g) were added to toluene (60ml) and the mixture was heated to reflux for 30 min. 4-Nitroso-N,N-dimethyl aniline (3g., 0.02m) was added in small portions (exothermic reaction) and heating under reflux, in argon, was continued for 3 hours. After cooling the mixture was evaporated to dryness under reduced pressure to leave a tarry residue which was extracted with hot acetic acid (2 x 100ml). The yield of reddish brown insoluble material remaining was 2.3g. The acetic acid extracts were neutralized by carefully adding sodium hydroxide liquor (40%) to pH 7: this resulted in a colour change, from violet to brown, and the precipitated tarry solid was collected. This was water washed several times, by decantation, and the remaining solid extracted with methylene chloride. The combined methylene chloride extracts were dried, solvent was removed and the residue chromatographed over siligel. The desired product was a dark red crystalline solid (0.57g., 12%), mp 152-154⁰C.

(H) Preparation of 1,5-Dimethyl-2-[(4-Dimethylamino)-phenylazo]-pyridinium iodide 5-Methyl-2-[(4-dimethylamino)-phenylazo]-pyridine (0.7g.) was added to methylene chloride (25ml), followed by iodomethane (11.4g), and the mixture heated to reflux for 8 hours. Ethyl acetate (30ml) was added and methylene chloride and residual iodomethane distilled off. On cooling a crystalline solid was collected, washed with further ethyl acetate (30ml) and dried.

Yield 1.4g. , mp 210 - 213⁰C.

Example 2

SYNTHESIS OF 1 -METHYL-2-r(4-DIMETHYUWIINO)-PHENYLAZOl- QUINOLINIUM IODIDE

(i) Preparation of disperse dye 2-[(4-dimethylamino)-phenylazo]-quinoline.

The scale (0.02m) and method employed were similar to that used for the preparation of 5-methyl-2-[(4-dimethylamino)-phenylazo]-pyridine, but replacing the 2-aminopyridine with 2-aminoquinoline (2.88g., 0.02m). Also, the toluene suspension of 2-aminoquonoline and sodamide was allowed to cool before adding the 4-nitroso-N,N-dimethyl aniline (3g., 0.02m). After removal of toluene the residual tar was stirred with methylene chloride and passed through silicagel. The eluate was collected, solvent removed and the residue was treated with ispropanol to yield a brown solid, mp 149 - 151⁰C.

(H) Preparation of 1-Methyl-2-[(4-dimethylamino)-phenylazo]-quinolinium iodide 2-[(4-Dimethylamino)-phenylazo]-quinoline (1.1g., 0.004m) and iodomethane (11.4g., 0.08m), in methylene chloride (20ml) were heated under reflux for 18hr. The mixture was allowed to cool and solid product, a greenish-violet microcrystalline solid was collected.

Yield 1.65g., 85%, mp 223 - 225⁰C. Example 3

UV-Vis spectra were recorded in water buffered to pH=7 of the dyes, Spectra were recorded in a 1 cm cell with an optical density of 1.

Dye Lambda max / nm

Example 4

The dyes listed below were added to a washing powder such that when 4g/L of the powder was dissolved in water the optical density at the lambda max of the dye in the range 400-700nm was 1 at 5cm. In this manner the same amount of colour was added to each powder. The washing powder contained 20% LAS surfactant, 30% Na2CO3, 40% NaCI, remainder minors included calcite and fluorescer and moisture. The washing powder was used to wash a 1 :1 :1 mixture of white woven cotton cloth, white polyester cloth and white nylon-elastane cloth. This simulates the mixed fabric types found in domestic wash loads. Washes were conducted in 26° French Hard water at 293K with a liquor to cloth ratio of 30:1. Washes took 30 minutes and were followed by 2, 1 minute rinsed in 26° French Hard water at 293K. Following the wash the fabrics were dried and their colour measured using a reflectometer (UV-excluded) and the colour expressed as CIE L^*a^*b^* values. The ΔE values (compared to control washed without dye) were calculated from this.

The experiment was repeated using wash water at 333K and rinse water at 293K.

The table below shows the ΔE values obtained in the experiment for cotton.

Dye ΔE ΔE 293K 333K

Comparative example

Comparative example

Basic Violet 35 is a cationic pyrazole monoazo 9.8 10.2 dye.

Comparative example

Basic Blue 159 is a cationic, 3,4-thiadiazole 5.1 5.6 monoazo dye. Comparative example

The dyes of the current invention gave more colour to the cloth as indicated by their larger ΔE values.

Exemplary Base Powder Formulations A, B, C and D

The powder formulations A, B, C and D were made up with the three pyridine/pyhdazine of example 3 at the level indicated. Exemplary Base Liquid Formulations A, B, C and D

The powder formulations A, B, C and D were made up with the three pyridine/pyhdazine of example 3 at the level indicated.

For both powder and liquids formulations, enzyme levels are given as percent pure enzyme. NI(7EO) refers to R-(OCH₂CH2)_nOH, where R is an alkyl chain of C12 to C15, and n is 7. NaLAS is linear alkyl benzene sulphonate (LAS) and (SLES(3EO)) is Ci₂-Ci₈ alkyl polyethoxylate (3.0) sulphate. Na Alkyl sulphate is PAS.

A three rinse conditioner formulation, for use in the rinse stage of the wash was also created. It contained 13.7wt% N,N-di(tallowoyloxyethyl)-N,N- dimethylammonium chloride, 1.5wt% perfume, 0.001wt% of the three pyridine/pyhdazine of example 3, remainder minors and water.

Claims

We Claim:

1. A laundry treatment composition comprising:

(i) from 2 to 70 wt% of a surfactant, from 0.005 to 2 wt %, of a fluoresces and from 0.0001 to 0.1 wt% of a blue or violet cationic pyridine/pyhdazine dye of the following structure:

wherein

X is selected from: N; CH; and, C-N=N-phenyl(B)-para-NR1 R2;

R₃ is selected from: H; alkyl; alkylaryl; and, aryl; and,

Ring A may be further condensed to a benzene ring.

2. A laundry detergent composition according to claim 1 , wherein the azo group is ortho to the quanternary nitrogen.

3. A laundry detergent composition according to claim 1 or 2, wherein Ri and R2 are selected from: H; polyethers, C1 -C8-alkyl which may be substituted by -OH, O-C1-C8-alkyl, -Cl, and -F, -CN; -C1-C8-alkyl-C(O)2-C1-C8-alkyl; - C1 -C8-alkyl-OC(O)-C1 -C8-alkyl;-C1 -C8-alkyl-phenyl; -C1 -C8-alkyl- naphthyl; phenyl; and, naphthyl, wherein the benzyl and phenyl may be substituted by a group selected from: -OC1 -C6-alkyl, -C1-C6-alkyl.

4. A laundry detergent composition according to any preceding claim, wherein R₃ is selected from: H, C1 -C8-alkyl, -d-Cβ-alkyl-phenyl; -C1 -C8-alkyl- naphthyl; phenyl; and, naphthyl.

5. A laundry detergent composition according to any preceding claim, wherein ring B carries up to two groups that are selected from: -Br; -Cl; -F; -NO2; - CN; -SO2-benzyl; -C(O)O-CI -C8-alkyl; -OC1 -C8-alkyl; -NHC(O)CI -C4- alkyl, -SO2-C1 -C8-alkyl; and -SO2-phenyl.

6. A laundry detergent composition according to claim 3, wherein Ri and R₂ are selected from: -H; -CH₃; -C₂H₅; -(CH₂)₃H; -(CH₂)₄H; -C₂H₄OH; -C₂H₄CI; -C₂H₄CN; -C₆H₅; -CH₂C₆H₅; -C₂H₄OCOCH₃; -C₂H₄COOCH₃; and, - C₂H₄OC₂H₄OH.

7. A laundry detergent composition according to claim 6, wherein Ri and R₂ are selected from: methyl and ethyl.

8. A laundry detergent composition according to claim 4, wherein R₃ is selected from methyl, ethyl and benzyl.

9. A laundry detergent composition according to any preceding claim wherein the fluorescer is selected from the group consisting of: sodium 2 (4-styryl-3- sulfophenyl)-2H-napthol[1 ,2-d]triazole, disodium 4,4'-bis{[(4-anilino-6-(N methyl-N-2 hydroxyethyl) amino 1 ,3,5-thazin-2-yl)]amino}stilbene-2-2' disulfonate, disodium 4,4'-bis{[(4-anilino-6-morpholino-1 ,3,5-triazin-2- yl)]amino} stilbene-2-2' disulfonate, and disodium 4,4'-bis(2- sulfostyryl)biphenyl.

10. A domestic method of treating a textile, the method comprising the steps of:

(i) treating a textile with an aqueous solution of the cationic pyridine/pyridazine dye as defined in any one of claims 1 to 8, the aqueous solution comprising from 1 ppb to 1 ppm of the cationic pyridine/pyridazine dye, and from 0 ppb to 1 ppm of another dye or pigment selected from: pigments, hydrophobic dyes and direct dyes; and, from 0.0 g/L to 3 g/L of a surfactant;

(ii) optionally rinsing the textile; and, (iii) drying the textile.

11. A domestic method of treating a textile, wherein the aqueous solution comprises 0.1 to 50 ppm of fluorescer.