GB2605843A

GB2605843A - Liquid cleansing composition

Info

Publication number: GB2605843A
Application number: GB2105468.9A
Authority: GB
Inventors: Woodhead Peter; Burgum Jennifer
Original assignee: Selden Research Ltd
Current assignee: Selden Research Ltd
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2022-10-19
Anticipated expiration: 2041-04-16
Also published as: GB2621755A; GB202105468D0; GB2605843B

Abstract

A liquid cleansing composition is disclosed comprising at least one alpha hydroxy acid, at least one anionic surfactant and at least one amphoteric surfactant, wherein the at least one amphoteric surfactant comprises a sultaine group. The at least one anionic surfactant and the at least one amphoteric surfactant are present in an amount of 3-20 % w/w, and the ratio of the at least one anionic surfactant to the at least one amphoteric surfactant is 2:1 or greater. The composition finds particular use as a biocidal hand washing composition where frequent hand washing is required.

Description

Liquid Cleansing Composition The invention relates to a liquid cleansing composition, in particular to a biocidal hand washing composition for frequent handwashing purposes.

Background to the Invention

There is a desire for skin cleansing products, and particularly hand soaps, to have a biocidal action. That is to say a hand soap product comprising a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The need is greatest in industries which handle food and in healthcare, but increasingly as viruses have become more common, such as SARS, NIERS and SARS-Cov-2, there is also a requirement for these products amongst consumers.

Liquid hand soaps are commonly based on either a traditional soap, i.e. a fatty acid neutralised with a common alkali such as potassium hydroxide, or based on an anionic surfactant. The anionic surfactant is normally sodium laureth sulphate, sodium lauryl sulphate, or the corresponding potassium and amine salts of these sulphates. Such soaps do not have the desired efficacy in eliminating pathogens in the short contact times associated with handwashing.

The simple addition of a biocide to an existing hand soap unfortunately does not produce the desired results. The most commonly used biocidal active substances, such as quaternary ammonium compounds and biguanides, lose their efficacy in the presence of soap and anionic surfactants. Reactive biocides, such as sodium hypochlorite, iodophors and hydrogen peroxide also tend to have limited compatibility with the substances commonly found in soaps and are considered to be too harsh on the skin for common use. Phenolic compounds, such as chloroxylenol, have been used in hand soaps but their harsh smell has limited their use. Triclosan was commonly used until environmental concerns curtailed it's use.

Of the remaining biocides, organic acids have found some favour in these products. Many organic acids are known to possess biocidal properties. In particular, the ones which have proven to be most useful for disinfection and with reasonable skin compatibility to make them useful in personal care applications are the alpha hydroxyl acids, commonly known as AHAs. Of those AHAs, most interest for biocidal formulations has fallen on lactic and glycolic acid It is known that the most common anionic surfactants, sodium lauryl sulphate and sodium lauryl ether sulphate, have a synergistic action with AHAs. As such it appears plausible that formulating a suitable biocidal hand soap conforming to EN 1276 should be possible. EN 1276 is the 60-second British and European quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas. This is exemplified and discussed further in "L-Lactic Acid A Safe Antimicrobial Ibr Home and Personal Care Formulations" to Boomsma, B. ct al in SOFW Journal: Home & Personal Care Ingredients & Formulations (2015), Vol. 10, No.141, pp.2-5.

However, such an assumption is misleading. Biocidal hand soaps are by their very nature used in areas which require frequent handwashing, such as in food preparation or healthcare.

This necessitates a very mild product with pleasant foaming characteristics to encourage frequent use and distribute the product efficiently in a volume of space, such as over the hands. Anionic surfactants in isolation have a relatively high irritation potential which, coupled with the inherent irritation potential of an acidic formulation, render such simplistic formulations unsatisfactory in the commercial environment.

It is commonly known for soaps without biocidal action that both the irritation potential and the foaming characteristics of anionic surfactants can be simultaneously improved by the addition of amphoteric surfactants, principally cocamidopropyl betaine.

This presents a problem. In attempting to make the formulation mild by the addition of amphoteric surfactant, the formulator has inhibited the efficacy of the lactic acid/anionic surfactant combination and thus needs to reformulate at a more aggressive pH to compensate for the reduction in efficacy. This antagonism renders such a formulation approach ineffective.

W02018/022016A1 discloses a liquid cleansing composition which includes a cleansing component and an antibacterial system. The antibacterial system includes an antibacterial agent and an antibacterial enhancing agent, wherein the weight ratio of the antibacterial agent to the antibacterial enhancing agent is greater than or equal to 0.30:1 and less than or equal to 0.65:1, wherein the suitability of the composition was tested in accordance with European Standard NF EN 1040 having a sixty-minute evaluation timeframe, which is incompatible with compositions suitable for frequent handw-ashing purposes.

There remains a need for a fast-acting, mild, skin cleansing preparation with substantial biocidal efficacy, such as the ability to pass EN 1276. There remains a need for a fast-acting, high foaming, skin cleansing preparation with substantial biocidal efficacy, such as the ability to pass EN 1276. A combination of mildness and foaming would be even more beneficial.

Summary of the Invention

The invention is set out in accordance with the appended claims. The invention relates to a liquid cleansing composition comprising at least one alpha hydroxy acid, at least one anionic surfactant, and at least one amphoteric surfactant wherein the at least one amphoteric surfactant comprises a sultaine group.

Formulations according to the invention have antiviral properties, and may be produced in the form of antibacterial soaps or hand dishwashing liquid compositions.

It has surprisingly been discovered that the reduction in efficacy afforded by the addition of amphoteric surfactants can be negated by careful selection of the amphoteric component. Amphoteric surfactants are ones which possess a zwitterion. That is to say part of the molecule incorporates both positively and negatively charged functional groups. The positively charged group is normally centred on a nitrogen atom, whilst the negatively charged group is normally a carboxylic acid group. The most common amphoteric surfactant used in hand soaps is cocamidopropyl betaine. A betaine is a specific type of zwitterion, being a neutral chemical compound with a positively charged cationic functional group, such as a quaternary ammonium or phosphonium cation that bears no hydrogen atom, and a negatively charged functional group, such as a carboxylate group, that may not be adjacent to the cationic site. An example of one of the first betaines to be discovered is N,N,Ntrimethylglycine (TN/G), shown below for reference: CH3 0 H30 N,N,N-trimethylglycine Whilst not being bound by theory, it is believed that most common amphoteric surfactants, such as those incorporating a betaine group, lose their anionic charge at such low pH by virtue of their carboxylic acid groups becoming protonated. Once the pH is sufficiently acidic for this process to take place, the amphoteric surfactant becomes predominantly cationic in nature. Cationic surfactants are the opposite charge to anionic surfactants and it is believed they inhibit the synergistic effect between the organic acid and the anionic surfactant. However, these behaviours are non-linear and interact with other formulation components and features such as ionic strength to make the effects unpredictable in practice.

In contrast, the particular amphoteric surfactants of the present invention do not derive their anionic groups from carboxylic acids, rather these anionic groups are the result of sulphonate groups which remain ionised at acidic pH. Consequently, the amphoteric surfactants of the present invention do not become cationic in nature in the presence of organic acids and, whilst this is unproven it is speculated that this does not inhibit the synergistic effect between anionic and amphoteric surfactants to the same degree.

This process can be illustrated by changing the amphoteric surfactant to a sultaine. Sultaines are similar to betaines. They have an analogous structure to betaines but with the carboxylic acid group substituted for a sulphonate group, as exemplified by formula I, which shows cocamidopropyl hydroxysultaine below for reference.

cocamidopropyl hydroxysulta ne Preferably the at least one amphoteric surfactant is selected from babassuamidopropyl hydroxysultaine, cannabisamidopropyl hydroxysultaine, capryl sultaine, cetyl sultaine, cocamidopropyl hydroxysultaine, coco-hydroxysultaine, coco-sultaine, erucamidopropyl hydroxysultaine, lauramidopropyl hydroxysultaine, lauryl hydroxysultaine, lauryl sultaine, myristamidopropyl hydroxysultaine, myristyl sultaine, oleamidopropyl hydroxysultaine, tallowamidopropyl hydroxysultaineor mixtures thereof Preferably the at least one amphoteric surfactant is a hydroxy sultaine Sultaines do not become cationic in nature in the presence of organic acids and as a result do 1() not inhibit the synergistic effect between anionic and amphoteric surfactants to the same degree. Preferably the at least one amphoteric surfactant is selected from formula Tin which n is from 6 to 18, preferably from 8 to 16. The alkyl chain represented by n may be saturated or unsaturated, mono unsaturated is preferred as this may provide higher foaming particularly in combination with n being from 9 to 13.

Preferably the at least one amphoteric surfactant is cocamidopropyl hydroxysultaine.

Cocamidopropyl hydroxysultaine has been demonstrated to show improved bactericidal activity over corresponding betaine-containing cleansing formulations Preferably the at least one amphoteric surfactant is present in an amount of 0.1-3.5 w/w.

While w/w is defined as the proportion of a particular substance within a mixture, as measured by weight or mass, in this case the skilled person will be aware that it is the mass of the component being referred to. 0.1-3.5 w/w translates as a composition comprising 0.13.5 grams of solute dissolved in 100 grams of solution.

Preferably the at least one alpha hydroxy acid is selected from citric acid, lactic acid, glycolic acid, malic acid, oxalic acid, carbonic acid, tartaric acid, mandelic acid or mixtures thereof. More preferably the alpha hydroxy acid is lactic acid, glycolic acid or mandelic acid, which have been shown to be less inhibited in combination with any anionic surfactant component to improve the mildness (skin-feel) of the formulation produced. More preferably the alpha hydroxy acid is lactic acid, glycolic acid or mandelic acid, which have been shown to be less inhibited in combination with any anionic surfactant component to improve the mildness (skin-feel) of the formulation produced. Most preferably the alpha hydroxy acid is lactic acid or glycolic acid, which have been shown to be less inhibited in combination with any anionic surfactant component to improve the mildness (skin-feel) of the formulation produced. Alternatively, mandelic acid can be preferred due to mildness and foaming in combination with sodium or potassium dodecyl sulphate. Alpha hydroxy acids are known to be good disinfectants and have reasonable skin compatibility to make them useful in personal care applications. A mixture of said acids may be used.

Preferably the at least one alpha hydroxy acid is present in an amount of 0.1-5 % w/w, further preferably in an amount of 0.5-3 % w/w, and highly preferably in an amount of 0.8-2 % w/w.

Preferably the at least one anionic surfactant comprises an alkyl sulphate group, an ethoxylated alkyl sulphate group, a sulphosuccinate group, a sulphoacetate group, a sarcosinate group, a linear alkyl aryl sulphonate group, a secondary alkane sulphonate group, an alpha olefin sulphonate group, an alkyl phosphate ester group or derivatives thereof More preferably the at least one anionic surfactant is selected from sodium laureth sulphate, sodium lauryl sulphate, sodium lauryl sulphoacetate or mixtures thereof Sodium laureth sulphate, sodium lauryl sulphate and sodium lauryl sulphoacetate may provide synergistic action with alpha hydroxy acids in personal care compositions.

Preferably the at least one anionic surfactant is present in an amount of 2,0-40,0% w/w, further preferably in an amount of 5.0-20% w/w, and highly preferably in an amount of 7.5-1 2.5 % w/w.

Preferably the at least one anionic surfactant and the at least one amphoteric surfactant are present in an amount of 3-20% w/w, further preferably in an in an amount of 5-15% w/w.

Soaps generally have anionic surfactant and amphoteric surfactants present in amounts of 5- % w/w, respectively, although the skilled person will note that the levels of the present invention are raised slightly because the acid inhibits the foaming action.

Preferably the ratio of the at least one anionic surfactant to the at least one amphoteric surfactant is 2:1 or greater, further preferably the ratio of the at least one anionic surfactant to the at least one amphoteric surfactant is 3:1 or greater. Typical formulations have a ratio of the at least one anionic surfactant to the at least one amphoteric surfactant being 3:1 or greater.

Preferably the composition further comprises a hydrolysed wheat protein or a derivative thereof, further preferably the hydrolysed wheat protein or a derivative thereof is cocodimonium hydroxypropyl hydrolyzed wheat protein. Hydrolysed wheat proteins are well known for their ability to moisturise the skin, particularly in such acid conditions which render the protein molecules slightly cationic.

Preferably the hydrolysed wheat protein or a derivative thereof is present in an amount of 0.1-1.0 % w/w.

Preferably the composition has a pH in the range 2-4.8, further preferably in the range from pH 2.5 to 4 and highly preferably in the range from pH 3 to 4.

The carrier or solvent of the liquid cleansing composition may be or may include water. Water of the liquid cleansing composition may be deionized water, demineralized water, and/or softened water. In an exemplary embodiment, the carrier of the liquid cleansing composition includes demineralized water and softened water. Water may make up the balance of the liquid cleansing composition. The amount of water in the liquid cleansing composition may include free water added and water introduced with other components or materials of the liquid cleansing composition. For example, the amount of the water in the liquid cleansing composition may include free water and water associated with the surfactants or any other component of the liquid cleansing composition. Preferably the composition comprises more than 65% water, more than 80% water, more than 70% water, more than 75% water, more than 80% water, more than 85% water, more than 90% water or more than 95% water.

The liquid cleansing composition may include one or more skin care agents. Any suitable skin care agents that do not adversely affect the stability and/or efficacy of the liquid cleansing composition may be used. In at least one embodiment, the skin care agent may include an emollient configured to maintain a soft, smooth, and pliable appearance to the skin. As is known by those skilled in the art, the emollients may function by remaining on the surface of the skin or in the stratum corneum to act as a lubricant, to reduce flaking, and/or to improve the appearance of the skin.

The skin care agents may generally include one or more polymers (e.g., polyvinylpyrrolidine), protein derivatives (e.g., derivatized hydrolyzed wheat protein such as cocodimonium hydroxypropyl hydrolyzed wheat protein), ethoxylated fatty ethers, cellulosics (e.g., hydroxyethylcellulose) and combinations thereof Illustrative skin care agents may include, but are not limited to, esters comprising an aliphatic alcohol having about 2 to about 18 carbon atoms condensed with an aliphatic or aromatic carboxylic acid including about 8 to about 20 carbon atoms (e.g., isopropyl myristate, decyl oleate or ethyl hexyl glycerine etc.). The esters may be straight chained or branched. In a preferred embodiment, the ester has a molecular weight of less than about 500 Daltons, Other skin care agents may include, but are not limited to, polyvinyl-pyrrolidone, polyquaternium-4, polyquaternium-7, polyquaternium-10, guar gum derivatives, hydroxypropylmethylcellulose, hydroxyethylcellulose, a polyethylene glycol, a methyl ether of a polyethylene glycol, quatemium-79, wheat germamidopropyl hydroxypropyl dimonium hydrolyzed wheat protein, stearyl methicone, dimethicone copolyol, dimethicone propyl PG betaine, poly(sodium styrene sulfonate), sorbitan oleate, steareth-2, steareth-21, isoceteth-20, PEG-7 glyceryl cocoate, PEG-75 lanolin, glycereth-26, PPG-5-ceteth-20, a C12-C2o alcohol, canola oil, glyceryl laurate, triglyceryl monostearate, glyceryl monostearate, vitamin E acetate, sunflower seed amidopropylethyldimonium ethylsulfate, sodium PEG-7 olive oil carboxylate, PPG-1 hydroxy ethyl caprylamide, PPG-2 hydroxy ethyl cocamide, mineral oil, petrolatum, aloe barbadensis, isostearamidopropylmorpholine lactate, strontium acetate, palmitamidopropyltrimonium chloride and combinations thereof The preferred skin care agent is a hydrolysed wheat protein or a derivative thereof More preferably the skin care agent is quaternized wheat protein. Most preferably the skin care agent is the is cocodimonium hydroxypropyl hydrolyzed wheat protein, which has been found to be particularly mild, such as in providing lower skin irritancy.

The liquid cleansing composition may include one or more additional optional ingredients.

Illustrative optional ingredients may include, but are not limited to, one or more dyes, fragrances or perfuming agents, buffers and buffering agents (e.g., inorganic phosphates, sulfates, and carbonates), pH adjusters (e.g., acids and/or bases), non-ionic surfactants, preservatives (e.g., parabens, sodium salicylate, sodium benzoate, etc.), thickeners, viscosity adjusters, water softeners, pearlising agents, essential oils, exfoliants, emollients, antioxidants, foam enhancers, chelating agents (e.g., EDTA, phosphates, etc.). °pacifiers, hydric solvents, hydrotropes, humectants, antimicrobials and combinations thereof Preferably the composition comprises an emollient ester selected from isopropyl myr state, decyl oleate or ethyl hexyl glycerine Basic pH adjusters may include ammonia; mono-, di-, and tri-alkyl amines; mono-, di-, and tri-alkanolamines; alkali metal and alkaline earth metal hydroxides and combinations thereof For example, the basic pH adjuster may be ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, monoethanol amine, triethylamine, isopropanolamine, diethanolamine, triethanolamine and combinations thereof Acidic pH adjusters may include mineral acids and polycarboxylic acids. The mineral acids may be or include hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid and combinations thereof The polycarboxylic acids may be or include citric acid, glycolic acid, lactic acid and combinations thereof Non-ionic surfactants may be or include amine oxides, alkyl polyglycosides, polysorbate 20, poloxamer 407, poloxamer 338, poloxamer 124 or mixtures thereof The non-ionic surfactants may also include, but are not limited to, ethoxylated and hydrogenated ethoxylated castor oils, such as those commonly designated as PEG INN castor oil or PEG INN hydrogenated castor oil, where NN" designates the number of ethylene oxide units polymerized onto the castor oil to form the non-ionic surfactant. For example, the non-ionic surfactants may be or include PEG 16, 20, 25, 30, 40, 50, 60, 80, 100, 200, and combinations thereof.

The liquid cleansing composition may have an acidic pH. In a preferred embodiment, the liquid cleansing composition is at least partially acidic. For example, the liquid cleansing composition may have a pH less than 7. In another example, the liquid cleansing composition may have a pH greater than or equal to 1 and less than 7. In a preferred embodiment, the liquid cleansing composition has a pH from 2 to 4.8, further preferably in the range from pH 2.5 to 4 and highly preferably in the range from pH 3 to 4.

Foam enhancers may be or include, but is not limited to, cocamide MEA (i.e., cocamide monoethanolamide), cocamide DEA, soyamide DEA, lauramide DEA, oleamide MIPA, stearamide ATEA, myristamide MEA, lauramide ATEA, capramide DEA, ricinoleamide DEA, myristamide DEA, stearamide DEA, oleylamide DEA, tallowamide DEA, lauramide MIPA, tallowamide MEA, isostearamide DEA, isostearamide MEA, and the like, and combinations thereof.

Humectants may be or include, but are not limited to, ascorbic acid, ascorbyl dipalmitate, acetamide MEA, glucose glutamate, glucuronic acid, TEA-lactate, TEA-PCA, corn syrup, fructose, glucose, glycerin, glycol, 1,2,6-hexanetriol, sodium lactate, sodium PC A, hydrogenated starch hydrolysate, inositol, lactic acid, lactose, mannitol, PC A, PEG-10 propylene glycol, polyamino sugar condensate, propylene glycol, pyridoxine dilaurate, saccharide hydrolysate, hydroxystearyl methyl glucamine, glucamine, maltitol, mannitol, methyl gluceth-10, methyl gluceth-20, riboflavin, PEG-4, PEG-6, PEG-8, PEG-9, PEG-10, PEG-12, PEG-14, PEG-16, PEG-18, PEG-20, PEG-32, PEG-40, glutamic acid, glycereth-7, glycereth-12, glycereth-26, saccharide isomerate, sorbeth-20, sorbitol, sucrose, thioglycerin, tris-(hydroxymethyl)nitromethane, tromethamine, histidine, PEG-75, PEG-135, PEG-150, PEG-200, PEG-5 pentaetythritol ether, polyglycetyl sorbitol, sorbitol, urea, xylitol and combinations thereof

Examples

Examples were prepared according to Table 1, Comparative Examples are denoted as Cl, C2, C3 eta and Inventive Examples are denoted simply as El, E2 etc. For the avoidance of any doubt, all amounts are expressed as l1) w/w with the remainder of the composition of each formulation being water.

Component Identity Examples Cl C2 C3 El E2 Anionic Sodium laureth 6.8 6.8 6.8 6.8 6.8 surfactant sulphate Anionic Sodium lauryl 2.2 2.2 2.2 2.2 2.2 surfactant sulphate Amphoteric Cocamidopropyl 0 2.8 0 0 0 surfactant betaine Amphoteric Sodium 0 0 2.8 0 0 surfactant cocoamphoacetate Amphoteric Cocamidopropyl 0 0 0 2.8 2.8 surfactant hydroxysultaine Alpha Lactic acid 1.5 1.5 1.5 1.5 0 hydroxy acid Alpha Glycolic acid 0 0 0 0 1.5 hydroxy acid pH adjuster Sodium To pH To pH To pH To pH To pH hydroxide 3.4-3.6 3.4-3.6 3.4 -3.6 3.4 -3.6 3.4-3.6 EN 1276 E. >5.32 < 1.95 < 1.95 > 5.32 > 5.29 Coli (pass) (fail) (fail) (pass) (pass) 60-second contact time Log reduction Table 1: Formulations prepared Tests were conducted in accordance with BS EN 1276:2019. This is the British and European quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas.

Samples of the product were diluted, which in the case of hand soap products is with equal parts hard water. These solutions are then mixed with a suspension of bacteria (selected from Pseuclomonas* aeruginosa, Escherichia colt K12, Staphylococcus aurens and Enterococcus helve) in a solution of an interfering substance. The mixture is maintained at the test temperature (20°C) for a given contact time, which in the case of hand soap products is no greater than 1 minute. After the given contact time, an aliquot is taken and the active ingredients in the portion are immediately neutralised, to prevent further biocidal action outside of the given contact time, and the numbers of surviving bacteria are enumerated. The efficacy of the disinfectant is calculated by subtracting the numbers of surviving bacteria from the number of cells in the test mixture at the beginning of the contact time. In the case of a bactericidal hand soap, the pass criteria stipulate that at least a log 3 reduction of the bacteria must be achieved.

Examples CI-C3 differ by way of choice of amphoteric surfactant used. Based upon the results for the two comparative examples Cl-C3, it quickly becomes apparent that addition of an amphoteric surfactant to an acidified solution of anionic surfactant inhibits the biocidal action. Turning to Inventive Examples El and E2, cocamidopropyl hydroxysultaine is used as a like for like replacement for cocamidopropyl betaine where an improved EN 1276 E. Coli 60-second contact time Log reduction is obtained. The selection of different alpha hydroxy acids is also demonstrated by Examples El and E2. The skilled formulator will note that whilst the careful use of the correct amphoteric surfactant modifies the properties of the anionic surfactant(s) to produce a desirable formulation, it would be especially desirable to also negate the negative effects of organic acids on the skin. In order to demonstrate this by way of Example, further Inventive Examples, E3 and E4, were prepared according to Table 2 below, where principle to negating the effects of organic acids is the use of hydrolysed wheat proteins and their derivatives as demonstrated. Again, for the avoidance of any doubt, all amounts are expressed as % w/w with the remainder of the composition of each formulation being water.

Component Identity Examples E3 E4 Anionic surfactant Sodium laureth 6.8 6.8 sulphate Anionic surfactant Sodium lauryl 2.2 2.2 sulphate Amphoteric surfactant Cocamidopropyl 2.8 2.8 hydroxysultaine Alpha hydroxy acid Lactic acid 1.5 1.5 Additional biocide Phenoxyethanol 1 1 Skin conditioner Quatemized wheat 1 0 protein Perfume Perfume 0.6 0.6 pH adjuster Sodium hydroxide To pH 3.1 -3.3 To pH 3.1 -3.3 EN 1276 E. Coli 3.98 (pass) >4.48 (pass) 60-second contact time Log reduction Table 2: Additional formulations prepared Hydrolysed wheat proteins are well known for their ability to moisturise the skin, particularly in such acid conditions which render the protein molecules slightly cationic and therefore more substantive to the skin. Even more beneficial are the quaternized variants which have permanent cationic charges which endow the molecules with further substansivity.

As is expected from the aforementioned teachings, such molecules have a deleterious effect on efficacy by negatively interacting with the anionic surfactants, as can be seen from the corresponding data for EN 1276 E Coli 60-second contact time Log reduction values demonstrated in Table 2.

The correct choice of amphoteric surfactant therefore brings the desired increase in sensory characteristics, such as mildness and foaminess, without such deleterious effects on efficacy. Such a high underlying efficacy of the formulation enables minor additions of other desirable substances which, whilst haying a slightly deleterious effect on efficacy, can substantially reduce the irritation potential of the organic acid to make a commercially viable formulation.

Claims

Claims: A liquid cleansing composition comprising: at least one alpha hydroxy acid, at least one anionic surfactant; and at least one amphoteric surfactant; wherein the at least one amphoteric surfactant comprises a sultaine group
2. The composition of claim 1, wherein the at least one amphoteric surfactant is selected 10 from babassuamidopropyl hydroxysultaine, cannabisamidopropyl hydroxysultaine, capryl sultaine, cetyl sultaine, cocamidopropyl hydroxysultaine, coco-hydroxysultaine, cocosultaine, erucamidopropyl hydroxysultaine, lauramidopropyl hydroxysultaine, lauryl hydroxysultaine, lauryl sultaine, myristamidopropyl hydroxysultaine, myristyl sultaine, oleamidopropyl hydroxysultaine, tallowamidopropyl hydroxysultaine or mixtures thereof 15
3. The composition of claim 1 or claim 2, wherein the at least one amphoteric surfactant is a hydroxy sultaine.
4. The composition of any of claim 1 to claim 3, wherein the at least one amphoteric surfactant is cocamidopropyl hydroxysultaine.
5. The composition of any preceding claim, wherein the at least one amphoteric surfactant is present in an amount of 0.1-3.5 % w/w.
6. The composition of any preceding claim, wherein the at least one alpha hydroxy acid is selected from citric acid, lactic acid, glycolic acid, malic acid, oxalic acid, carbonic acid, mandelic acid or mixtures thereof.
7. The composition of claim 6, wherein the at least one alpha hydroxy acid is lactic acid, glycolic acid or mandelic acid.
8. The composition of any preceding claim, wherein the at least one alpha hydroxy acid is present in an amount of 0.1-5 % w/w.
9 The composition of any preceding claim, wherein the at least one anionic surfactant comprises a sulphosuccinate group, a sulphoacetate group or derivatives thereof
10. The composition of any of claim 1 to claim 8, wherein the at least one anionic surfactant is selected from sodium laureth sulphate, sodium lauryl sulphate, sodium lauryl sulphoacetate or mixtures thereof
11. The composition of any preceding claim, wherein the at least one anionic surfactant is present in an amount of 2.0-40.0 % w/w.
12. The composition of any preceding claim, wherein the at least one anionic surfactant and the at least one amphoteric surfactant are present in an amount of 3-20 ')/ii w/w.
13. The composition of claim 12, wherein the at least one anionic surfactant and the at least one amphoteric surfactant are present in an amount of 5-15 % w/w.
14. The composition of any preceding claim, wherein the ratio of the at least one anionic surfactant to the at least one amphoteric surfactant is 2:1 or greater.
15. The composition of claim 14, wherein the ratio of the at least one anionic surfactant to the at least one amphoteric surfactant is 3:1 or greater.
16. The composition of any preceding claim, further comprising a hydrolysed wheat protein or a derivative thereof
17. The composition of claim 16, wherein the hydrolysed wheat protein or a derivative thereof is cocodimonium hydroxypropyl hydrolyzed wheat protein.
18. The composition of claim 16 or claim 17, wherein the hydrolysed wheat protein or a derivative thereof is present in an amount of 0.1-1.0 % w/w.
19. The composition of any preceding claim, having a pH in the range 2-4.8.
20. The composition of any preceding claim, further comprising one or more additional ingredients selected from one or more dyes, fragrances, perfuming agents, buffers and buffering agents, pH adjusters, non-ionic surfactants, preservatives, thickeners, viscosity adjusters, water softeners, pearlising agents, essential oils, exfoliants, emollients, antioxidants, foam enhancers, chelating agents, opacifiers, hydric solvents, hydrotropes, humectants, antimicrobials and combinations thereof.
21. The composition of claim 20, comprising an emollient ester selected from isopropyl myri state, decyl oleate or ethyl hexyl glycerine.
22. The composition of any preceding claim, wherein the balance of the composition is water.
23. The composition of any preceding claim, wherein the composition comprises more than 80% water.
24. The composition of any preceding claim, wherein the composition consists of the specified components.