Field of the Invention

The present invention relates to liquid laundry detergents having enhanced oily soil removal activity.

Background and Prior Art

There is a continuing need to improve the cleaning performance of liquid laundry detergents as consumers move to lower wash temperatures and seek products with improved environmental credentials.

One route to improving the environmental profile of liquid laundry detergents is the addition of highly weight efficient or multi-functional materials to replace traditional materials such as surfactants, resulting in a lower overall chemicals usage.

WO2009153184 describes such an approach, where the preferred formulations have high amounts of soil release polymer and antiredeposition polymer relative to the total detersive surfactants level.

Whilst liquid laundry detergents of the type described in WO2009153184 have proven to be successful, the effective removal of oily soils from fabric remains as a persistent problem area.

The present invention addresses this problem.

Summary of the Invention

The present invention provides a liquid laundry detergent composition comprising: a) from 8 to 15% (by weight based on the total weight of the composition) of anionic surfactants selected from linear alkylbenzene sulfonates and mixtures thereof with alkyl ether sulfate; b) from 1 to 5% (by weight based on the total weight of the composition) of nonionic surfactants selected from Cs to Cie primary or secondary linear or branched alcohol ethoxylates with an average of from 2 to 40 moles of ethylene oxide per mole of alcohol; c) from 0.5 to 15% (by weight based on the total weight of the composition) of

polymeric cleaning boosters selected from antiredeposition polymers, soil release polymers and mixtures thereof; in which the total amount of anionic surfactants (a) + nonionic surfactants (b) ranges from 9 to 20% (by weight based on the total weight of the composition); and in which the weight ratio of anionic surfactants (a) to nonionic surfactants (b) ranges from 3:1 to 12:1.

Detailed Description and Preferred Embodiments

Liquid laundry detergents

The term“laundry detergent” in the context of this invention denotes formulated compositions intended for and capable of wetting and cleaning domestic laundry such as clothing, linens and other household textiles. The term“linen” is often used to describe certain types of laundry items including bed sheets, pillow cases, towels, tablecloths, table napkins and uniforms. Textiles can include woven fabrics, non-woven fabrics, and knitted fabrics; and can include natural or synthetic fibres such as silk fibres, linen fibres, cotton fibres, polyester fibres, polyamide fibres such as nylon, acrylic fibres, acetate fibres, and blends thereof including cotton and polyester blends.

Examples of liquid laundry detergents include heavy-duty liquid laundry detergents for use in the wash cycle of automatic washing machines, as well as liquid fine wash and liquid colour care detergents such as those suitable for washing delicate garments (e.g those made of silk or wool) either by hand or in the wash cycle of automatic washing machines.

The term“liquid” in the context of this invention denotes that a continuous phase or predominant part of the composition is liquid and that the composition is flowable at 15°C and above. Accordingly the term“liquid” may encompass emulsions, suspensions, and compositions having flowable yet stiffer consistency, known as gels or pastes. The viscosity of the composition may suitably range from about 200 to about 10,000 mPa.s at 25°C at a shear rate of 21 sec ¹ . This shear rate is the shear rate that is usually exerted on the liquid when poured from a bottle. Pourable liquid detergent compositions generally have a viscosity of from 200 to 2,500 mPa.s, preferably from 200 to 1500 mPa.s.

Liquid detergent compositions which are pourable gels generally have a viscosity of from 1 ,500 mPa.s to 6,000 mPa.s, preferably from 1 ,500 mPa.s to 2,000 mPa.s.

A composition of the invention may generally comprise from 5 to 95%, preferably from 10 to 90%, more preferably from 15 to 85% water (by weight based on the total weight of the composition). The composition may also incorporate non-aqueous carriers such as hydrotropes, co-solvents and phase stabilizers. Such materials are typically low molecular weight, water-soluble or water-miscible organic liquids such as C1 to C5 monohydric alcohols (such as ethanol and n- or i-propanol); C2 to C6 diols (such as monopropylene glycol and dipropylene glycol); C3 to C9 triols (such as glycerol);

polyethylene glycols having a weight average molecular weight (M _w ) ranging from about 200 to 600; C1 to C3 alkanolamines such as mono-, di- and triethanolamines; and alkyl aryl sulfonates having up to 3 carbon atoms in the lower alkyl group (such as the sodium and potassium xylene, toluene, ethylbenzene and isopropyl benzene (cumene) sulfonates).

Mixtures of any of the above described materials may also be used.

Non-aqueous carriers, when included, may be present in an amount ranging from 0.1 to 20%, preferably from 1 to 15%, and more preferably from 3 to 12% (by weight based on the total weight of the composition). The composition of the invention preferably has a pH in the range of 5 to 9, more preferably 6 to 8, when measured on dilution of the composition to 1 % using

demineralised water.

The composition of the invention comprises from 8 to 15% (by weight based on the total weight of the composition) of anionic surfactants (a) selected from linear alkylbenzene sulfonates and mixtures thereof with alkyl ether sulfate.

Linear alkylbenzene sulfonates (LAS) for use in the invention generally contain from about 10 to about 18 carbon atoms in the linear alkyl chain. Commercial LAS is a mixture of closely related isomers and alkyl chain homologues, each containing an aromatic ring sulfonated at the“para” position and attached to a linear alkyl chain at any position except the terminal carbons. The linear alkyl chain typically has a chain length of from 11 to 15 carbon atoms, with the predominant materials having a chain length of from 12 to 14 carbon atoms. Each alkyl chain homologue consists of a mixture of all the possible sulfophenyl isomers. except for the 1 -phenyl isomer. LAS is produced as a salt by neutralizing it with a suitable counterion, which is typically selected from alkali metals such as sodium and potassium (preferably sodium); or ammoniacal counterions such as ammonium, monoethanolamine (MEA) and triethanolamine (TEA). Mixtures of such counterions may also be employed. LAS may be formulated into compositions in acid (i.e. HLAS) form and then at least partially neutralized in-situ.

Alkyl ether sulfates (AES) for use in the invention generally contain a straight or branched chain alkyl group having 10 to 16 carbon atoms. Preferred types of AES have a structure corresponding to general formula (I):

R-0-(CH ₂ CH ₂ -0) _n -S0 ₃ -M ⁺ (I) in which R is a straight or branched chain alkyl group having 10 to 16 carbon atoms, n is a number that represents the degree of ethoxylation and ranges from 2 to 4, and M is an alkali metal, ammonium or alkanolammonium cation; In general formula (I), M is preferably sodium, potassium, ammonium or ethanolamine, R is preferably a linear alkyl group having from 12 to 14 carbon atoms, and the average degree of ethoxylation n preferably ranges from 2.5 to 3.5.

Commercially produced AES generally contain a mixture of homologues and the degree of ethoxylation is a statistical average value which may be an integer or a fraction. The value of n in general formula (I) is governed by the starting molar ratio of ethylene oxide to aliphatic alcohol in the ethoxylation reaction and the temperature, time and catalytic conditions under which the ethoxylation reaction takes place.

A commercially produced AES having general formula (I) will usually comprise a mixture of homologues in which from 55 to 80 mol% of the total mixture is made up of homologues with ethoxy chains of 5EO or less (down to OEO, i.e. unethoxylated alkyl sulfate), with the remainder of the mixture made up of homologues with ethoxy chains of 6EO or more (up to about 10EO). Higher homologues (e.g. up to about 15EO) may also be present in small amounts (typically no more than 1 to 2 mol% of the total mixture per individual homologue).

Mixtures of any of the above described materials may also be used.

A preferred mixture of anionic surfactants (a) for use in the invention contains:

(ai) C11 to C15 LAS, and

(aii) C12 to C _M linear AES with an average degree of ethoxylation ranging from 2.5 to 3.5.

The weight ratio of (ai):(aii) in the mixture preferably ranges from 1 :1 to 4:1 , more preferably from 2:1 to 3:1.

The total amount of anionic surfactants (a) in a composition of the invention preferably ranges from 10 to 14% (by weight based on the total weight of the composition).

The composition of the invention comprises from 1 to 5% (by weight based on the total weight of the composition) of nonionic surfactants (b). Preferred aliphatic alcohol ethoxylates for use in the invention may be selected from C12 to C15 primary linear alcohol ethoxylates with an average of from 3 to 20, more preferably from 5 to 10, most preferably 7 to 9 moles of ethylene oxide per mole of alcohol.

Mixtures of any of the above described materials may also be used.

The total amount of nonionic surfactants (b) in a composition of the invention preferably ranges from 1 to 3.5% (by weight based on the total weight of the composition).

The weight ratio of anionic surfactants (a) to nonionic surfactants (b) in a composition of the invention preferably ranges rom 3:1 to 10:1 , more preferably from 3.5:1 to 9.5:1.

The total amount of anionic surfactants (a) + nonionic surfactants (b) in a composition of the invention preferably ranges from 11 to 18%, more preferably from 12 to 16% (by weight based on the total weight of the composition).

A particularly preferred composition of the invention comprises, as the anionic surfactants

(a) and nonionic surfactants (b):

(ai) from 7 to 1 1% (by weight based on the total weight of the composition) of Cn to C15 LAS;

(aii) from 2 to 5% (by weight based on the total weight of the composition) of C12 to C14 linear AES with an average degree of ethoxylation ranging from 2.5 to 3.5, and

(b) from 1 to 3.5% (by weight based on the total weight of the composition) of C12 to C15 primary linear alcohol ethoxylate with an average of from 5 to 10 moles of ethylene oxide per mole of alcohol.

The composition of the invention comprises from 0.5 to 15% (by weight based on the total weight of the composition) of polymeric cleaning boosters (c) selected from antiredeposition polymers, soil release polymers and mixtures thereof. SRPs help to improve the detachment of soils from fabric by modifying the fabric surface during washing. The adsorption of a SRP over the fabric surface is promoted by an affinity between the chemical structure of the SRP and the target fibre.

SRPs for use in the invention may include a variety of charged (e.g. anionic) as well as non-charged monomer units and structures may be linear, branched or star-shaped. The SRP structure may also include capping groups to control molecular weight or to alter polymer properties such as surface activity. The weight average molecular weight (M _w ) of the SRP may suitably range from about 1000 to about 20,000 and preferably ranges from about 1500 to about 10,000.

SRPs for use in the invention may suitably be selected from copolyesters of dicarboxylic acids (for example adipic acid, phthalic acid or terephthalic acid) with diols (for example ethylene glycol or propylene glycol) and polydiols (for example polyethylene glycol or polypropylene glycol). The copolyester may also include monomeric units substituted with anionic groups, such as for example sulfonated isophthaloyl units. Examples of such materials include oligomeric esters produced by transesterification/oligomerization of poly(ethyleneglycol) methyl ether, dimethyl terephthalate (“DMT”), propylene glycol (“PG”) and poly(ethyleneglycol) (“PEG”); partly- and fully-anionic-end-capped oligomeric esters such as oligomers from ethylene glycol (“EG”), PG, DMT and Na-3,6-dioxa-8- hydroxyoctanesulfonate; nonionic-capped block polyester oligomeric compounds such as those produced from DMT, Me-capped PEG and EG and/or PG, or a combination of DMT, EG and/or PG, Me-capped PEG and Na-dimethyl-5-sulfoisophthalate, and copolymeric blocks of ethylene terephthalate or propylene terephthalate with polyethylene oxide or polypropylene oxide terephthalate.

Other types of SRP for use in the invention include cellulosic derivatives such as hydroxyether cellulosic polymers, Ci-C alkylcelluloses and C ₄ hydroxyalkyl celluloses; polymers with poly(vinyl ester) hydrophobic segments such as graft copolymers of poly(vinyl ester), for example C -C vinyl esters (such as poly(vinyl acetate)) grafted onto polyalkylene oxide backbones; poly(vinyl caprolactam) and related co-polymers with monomers such as vinyl pyrrolidone and/or dimethylaminoethyl methacrylate; and polyester-polyamide polymers prepared by condensing adipic acid, caprolactam, and polyethylene glycol.

Preferred SRPs for use in the invention include copolyesters formed by condensation of terephthalic acid ester and diol, preferably 1 ,2 propanediol, and further comprising an end cap formed from repeat units of alkylene oxide capped with an alkyl group. Examples of such materials have a structure corresponding to general formula (I):

in which R ¹ and R ² independently of one another are X-(OC2H4) _n -(OC3H6) _{m ;}

in which X is Ci _-4 alkyl and preferably methyl;

n is a number from 12 to 120, preferably from 40 to 50;

m is a number from 1 to 10, preferably from 1 to 7; and

a is a number from 4 to 9.

Because they are averages, m, n and a are not necessarily whole numbers for the polymer in bulk.

Mixtures of any of the above described materials may also be used.

The total amount of SRP in a composition of the invention preferably ranges from 0.1 to 5%, more preferably from 0.2 to 2% (by weight based on the total weight of the composition) of one or more SRPs (such as, for example, the copolyesters of general formula (I) as are described above).

Anti-redeposition polymers stabilise the soil in the wash solution thus preventing redeposition of the soil. Suitable anti-redeposition polymers for use in the invention include alkoxylated polyethyleneimines. Polyethyleneimines are materials composed of ethylene imine units -CH2CH2NH- and, where branched, the hydrogen on the nitrogen is replaced by another chain of ethylene imine units. Preferred alkoxylated

polyethylenimines for use in the invention have a polyethyleneimine backbone of about 300 to about 10000 weight average molecular weight (M _w ). The polyethyleneimine backbone may be linear or branched. It may be branched to the extent that it is a dendrimer. The alkoxylation may typically be ethoxylation or propoxylation, or a mixture of both. Where a nitrogen atom is alkoxylated, a preferred average degree of alkoxylation is from 10 to 30, preferably from 15 to 25 alkoxy groups per modification. A preferred material is ethoxylated polyethyleneimine, with an average degree of ethoxylation being from 10 to 30, preferably from 15 to 25 ethoxy groups per ethoxylated nitrogen atom in the polyethyleneimine backbone. Another type of suitable anti-redeposition polymer for use in the invention includes cellulose esters and ethers, for example sodium

carboxymethyl cellulose.

Mixtures of any of the above described materials may also be used.

The total amount of anti-redeposition polymer in a composition of the invention preferably ranges from 0.05 to 6%, more preferably from 0.5 to 5% (by weight based on the total weight of the composition).

A composition of the invention preferably comprises, as the polymeric cleaning boosters (c), a mixture of SRP (as further described above) and antiredeposition polymer (as further described above).

A particularly preferred composition of the invention comprises, as the polymeric cleaning boosters (c):

(ci) from 0.2 to 2% (by weight based on the total weight of the composition) of SRP selected from copolyesters of dicarboxylic acids with diols and polydiols, and

(cii) from 0.5 to 5% (by weight based on the total weight of the composition) of anti- redeposition polymer selected from ethoxylated polyethyleneimines with a

polyethyleneimine backbone of 300 to 10000 weight average molecular weight (M _w ).and an average degree of ethoxylation of from 15 to 25 ethoxy groups per ethoxylated nitrogen atom in the polyethyleneimine backbone. The total amount of polymeric cleaning boosters (c) in a composition of the invention preferably ranges from 0.5 to 10%, more preferably from 1 to 5% (by weight based on the total weight of the composition).

Optional ingredients

A composition of the invention may contain further optional ingredients to enhance performance and/or consumer acceptability, as follows:

Cosurfactants

A composition of the invention may contain one or more cosurfactants (such as amphoteric (zwitterionic) and/or cationic surfactants) in addition to the anionic surfactants (a) and nonionic surfactants (b) described above.

Specific cationic surfactants include Csto Cis alkyl dimethyl ammonium halides and derivatives thereof in which one or two hydroxyethyl groups replace one or two of the methyl groups, and mixtures thereof. Cationic surfactant, when included, may be present in an amount ranging from about 0.1 to about 5% (by weight based on the total weight of the composition).

Specific amphoteric (zwitterionic) surfactants include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines), alkyl glycinates, alkyl carboxyglycinates, alkyl amphoacetates, alkyl amphopropionates, alkylamphoglycinates, alkyl amidopropyl hydroxysultaines, acyl taurates and acyl glutamates, 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. Amphoteric (zwitterionic) surfactant, when included, may be present in an amount ranging from about 0.1 to about 5% (by weight based on the total weight of the composition).

Mixtures of any of the above described materials may also be used. Sequestrants

A composition of the invention will preferably include one or more sequestrants.

Sequestrants may help to enhance or maintain the cleaning efficiency of the composition, primarily by coordinating (i.e. binding) those metal ions which might otherwise interfere with cleaning action. Examples of such metal ions which are commonly found in wash water include divalent and trivalent metal ions such as ferrous, ferric, manganese, copper magnesium and calcium ions.

Suitable sequestrants for use in the invention include phosphonates, in acid and/or salt form. When utilized in salt form, alkali metal (e.g. sodium and potassium) or

alkanolammonium salts are preferred. Specific examples of such materials include aminotris(methylene phosphonic acid) (ATMP), 1-hydroxyethylidene diphosphonic acid (HEDP) and diethylenetriamine penta(methylene phosphonic acid (DTPMP) and their respective sodium or potassium salts. A preferred phosphonate sequestrant for use in the invention is HEDP.

Other types of sequestrant for use in the invention include polycarboxylates, in acid and/or salt form. When utilized in salt form, alkali metal (e.g. sodium and potassium) or alkanolammonium salts are preferred. Specific examples of such materials include sodium and potassium citrates, sodium and potassium tartrates, the sodium and potassium salts of tartaric acid monosuccinate, the sodium and potassium salts of tartaric acid disuccinate, sodium and potassium ethylenediaminetetraacetates, sodium and potassium N(2-hydroxyethyl)-ethylenediamine triacetates, sodium and potassium nitrilotriacetates and sodium and potassium N-(2-hydroxyethyl)-nitrilodiacetates.

Polymeric polycarboxylates may also be used, such as polymers of unsaturated monocarboxylic acids (e.g. acrylic, methacrylic, vinylacetic, and crotonic acids) and/or unsaturated dicarboxylic acids (e.g. maleic, fumaric, itaconic, mesaconic and citraconic acids and their anhydrides). Specific examples of such materials include polyacrylic acid, polymaleic acid, and copolymers of acrylic and maleic acid. The polymers may be in acid, salt or partially neutralised form and may suitably have a molecular weight (Mw) ranging from about 1 ,000 to 100,000, preferably from about 2,000 to about 85,000, and more preferably from about 2,500 to about 75,000. A preferred polycarboxylate sequestrant for use in the invention is citrate (in acid and/or salt form).

Mixtures of any of the above described materials may also be used.

Sequestrant, when included, may be present in an amount ranging from about 0.1 to about 10%, preferably from about 0.5 to about 5%, more preferably from about 1 to about 4% (by weight based on the total weight of the composition).

Fatty Acid

A composition of the invention may in some cases contain one or more fatty acids and/or salts thereof.

Suitable fatty acids in the context of this invention include aliphatic carboxylic acids of formula RCOOH, where R is a linear or branched alkyl or alkenyl chain containing from 6 to 24, more preferably 10 to 22, most preferably from 12 to 18 carbon atoms and 0 or 1 double bond. Preferred examples of such materials include saturated C12-18 fatty acids such as lauric acid, myristic acid, palmitic acid or stearic acid; and fatty acid mixtures in which 50 to 100% (by weight based on the total weight of the mixture) consists of saturated C12-18 fatty acids. Such mixtures may typically be derived from natural fats and/or optionally hydrogenated natural oils (such as coconut oil, palm kernel oil or tallow).

The fatty acids may be present in the form of their sodium, potassium or ammonium salts and/or in the form of soluble salts of organic bases, such as mono-, di- or triethanolamine.

Mixtures of any of the above described materials may also be used.

Fatty acids and/or their salts, when included, may be present in an amount ranging from about 0.25 to 5%, more preferably from 0.5 to 5%, most preferably from 0.75 to 4% (by weight based on the total weight of the composition). Rheology modifiers

A composition of the invention may comprise one or more rheology modifiers. Examples of such materials include polymeric thickeners and/or structurants such as

hydrophobically modified alkali swellable emulsion (HASE) copolymers. Exemplary HASE copolymers for use in the invention include linear or crosslinked copolymers that are prepared by the addition polymerization of a monomer mixture including at least one acidic vinyl monomer, such as (meth)acrylic acid (i.e. methacrylic acid and/or acrylic acid); and at least one associative monomer. The term“associative monomer” in the context of this invention denotes a monomer having an ethylenically unsaturated section (for addition polymerization with the other monomers in the mixture) and a hydrophobic section. A preferred type of associative monomer includes a polyoxyalkylene section between the ethylenically unsaturated section and the hydrophobic section. Preferred HASE copolymers for use in the invention include linear or crosslinked copolymers that are prepared by the addition polymerization of (meth)acrylic acid with (i) at least one associative monomer selected from linear or branched C8-C40 alkyl (preferably linear C12- C22 alkyl) polyethoxylated (meth)acrylates; and (ii) at least one further monomer selected from C1-C4 alkyl (meth) acrylates, polyacidic vinyl monomers (such as maleic acid, maleic anhydride and/or salts thereof) and mixtures thereof. The polyethoxylated portion of the associative monomer (i) generally comprises about 5 to about 100, preferably about 10 to about 80, and more preferably about 15 to about 60 oxyethylene repeating units.

Mixtures of any of the above described materials may also be used.

When included, a composition of the invention will preferably comprise from 0.1 to 5% (by weight based on the total weight of the composition) of one or more polymeric thickeners such as, for example, the HASE copolymers which are described above.

Compositions of the invention may also have their rheology modified by use of one or more external structurants which form a structuring network within the composition. Examples of such materials include hydrogenated castor oil, microfibrous cellulose and citrus pulp fibre. The presence of an external structurant may provide shear thinning rheology and may also enable materials such as encapsulates and visual cues to be suspended stably in the liquid.

Enzymes

A composition of the invention may comprise an effective amount of one or more enzyme selected from the group comprising, pectate lyase, protease, amylase, cellulase, lipase, mannanase and mixtures thereof. The enzymes are preferably present with

corresponding enzyme stabilizers.

Further Optional Ingredients

A composition of the invention may contain further optional ingredients to enhance performance and/or consumer acceptability. Examples of such ingredients include foam boosting agents, preservatives (e.g. bactericides), polyelectrolytes, anti-shrinking agents, anti-wrinkle agents, anti-oxidants, sunscreens, anti-corrosion agents, drape imparting agents, anti-static agents, ironing aids, colorants, pearlisers and/or opacifiers, and shading dye. Each of these ingredients will be present in an amount effective to accomplish its purpose. Generally these optional ingredients are included individually at an amount of up to 5% (by weight based on the total weight of the composition).

Packaging and dosing

A composition of the invention may be packaged as unit doses in polymeric film soluble in the wash water. Alternatively, a composition of the invention may be supplied in multidose plastics packs with a top or bottom closure. A dosing measure may be supplied with the pack either as a part of the cap or as an integrated system.

A method of laundering fabric using a composition of the invention will usually involve diluting the dose of composition to obtain a wash liquor, and washing fabrics with the wash liquor so formed. The method of laundering fabric may suitably be carried out in a top-loading or front-loading automatic washing machine, or can be carried out by hand.

In automatic washing machines, the dose of composition is typically put into a dispenser and from there it is flushed into the machine by the water flowing into the machine, thereby forming the wash liquor. Dosages for a typical front-loading washing machine (using 10 to 15 litres of water to form the wash liquor) may range from about 10 ml to about 60 ml, preferably about 15 to 40 ml. Dosages for a typical top-loading washing machine (using from 40 to 60 litres of water to form the wash liquor) may be higher, e.g. up to about 100 ml. Lower dosages of composition (e.g. 50 ml or less) may be used for hand washing methods (using about 1 to 10 litres of water to form the wash liquor).

A subsequent aqueous rinse step and drying the laundry is preferred. Any input of water during any optional rinsing step(s) is not included when determining the volume of the wash liquor. The laundry drying step can take place either in an automatic dryer or in the open air.

The invention will now be further described with reference to the following non-limiting Examples.

EXAMPLES

All weight percentages are by weight based on total weight unless otherwise specified. Liquid laundry detergent formulations were prepared by sequential mixing of the ingredients as shown in Table 1. Compositions according to the invention are indicated by a number; and comparative examples (not according to the invention) are indicated by a letter. Table 1

The detergents were used to wash a lard stain on cotton (lard and violet dye stain on CN42 sourced from Warwick Equest) in a Terg-o-tometer for 30 minutes in 1 litre of 24° French Hard water at 313K at a dose of 2.33g/L. 40g total fabric was placed in the Terg-o-tometer being an equal weight mix of woven cotton and polyester.

Following the wash the stains were rinsed, dried and then the colour measured by a reflectometer and expressed as the After wash SRI, which is After wash SRI = 100 - DE Where DE is the difference in colour of the stain cloth compared to an unstained cloth. A higher SRI value indicates cleaner cloths. Each experiment was repeated 6 times and the statistical difference calculated using a Tukey test. The results are shown below in Table 2.

Table 2.

Connecting letter denotes no significant difference at 95% using Tukey test

It can be seen from the results that Examples 1 and 2 according to the invention each provide significantly better cleaning than the comparative Example A, as shown by the higher SRI.