WO1998022086A1

WO1998022086A1 - Aqueous cleansing composition

Info

Publication number: WO1998022086A1
Application number: PCT/EP1997/005918
Authority: WO
Inventors: Stuart Keith Pratley
Original assignee: Unilever Plc; Unilever N.V.
Priority date: 1996-11-18
Filing date: 1997-10-20
Publication date: 1998-05-28
Also published as: US6001787A; CA2269968A1; AR009611A1; JP2000509722A; EP0946142B1; ID21756A; DE69732787T2; BR9713081A; US6569825B1; DE69732787D1; ES2238732T3; AU5121298A; EP0946142A1; JP3675846B2; CN1244791A; IN190004B; HUP9904246A3; CN1140260C; GB9623935D0; HUP9904246A2

Abstract

An aqueous cleansing composition, which comprises: (a) a short-chain anionic surfactant chosen from C6-C9 alkyl ether sulphates, C8-C11 acyl lactylates, C6-C9 acyl methyl taurates, C6-C9 acyl isethionates, C6-C11 fatty acid soaps, C6-C9 alkyl sulphates, C6-C11 acyl sarcosinates, C6-C9 alkyl sulphosuccinates, C6-C9 alkyl ether sulphosuccinates, or mixtures thereof; (b) a long-chain anionic surfactant chosen from C13-C18 alkyl ether sulphates, C13-C18 acyl lactylates, C13-C16 acyl methyl taurates, C13-C15 acyl isethionates, C13-C16 alkyl sulphates, C13-C16 acyl sarcosinates, C13-C16 alkyl sulphosuccinates, C13-C16 alkyl ether sulphosuccinates, or mixtures thereof; (c) optionally, a medium-chain anionic surfactant chosen from C10-C12 alkyl ether sulfates, C12 acyl lactylates, C10-C12 acyl methyl taurates, C10-C12 acyl isethionates, C10-C12 alkyl sulphates, C12 acyl sarcosinates, C10-C12 alkyl sulphosuccinates, C10-C12 alkyl ether sulphosuccinates, or mixtures thereof, and (d) water; wherein (i) at least one of the surfactants (a) and (b) is selected from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates and the acyl isethionates, or the short-chain anionic surfactant (a) is a C6-C11 fatty acid soap; (ii) if surfactant (c) is present, then the surfactants (a), (b) and (c) are present in an amount such that the weight ratio of (c): [(a) + (b)] is less than 1:1.

Description

AQUEOUS CLEANSING COMPOSITION

Field of the Invention

The invention relates to aqueous cleansing compositions. In particular, the invention is concerned with aqueous cleansing compositions suitable for cleaning human skin and hair, which comprise a combination of certain specific long- chain and short-chain surfactants. The compositions are not only very mild but also show an excellent lather performance .

Background to the Invention and Prior Art

In the recent past it has become more and more important for consumers that aqueous cleansing compositions are high foaming as well as mild. These combined properties are especially useful if the cleansing compositions are to be topically applied to human skin and hair. Consequently, efforts have been made to provide washing products, such as hair shampoos, shower gels and facial wash foams, showing these two properties. The major problem to provide such products resides in the fact that both properties tend to be mutually incompatible. While high lathering surfactants are generally very harsh, mild surfactants tend to give insufficient lather.

In the past attempts have been made to overcome these problems by combining harsh surfactants generating sufficient lather with very mild co-surf ctants.

US-A-3 , 728, 447 (C J Patterson) discloses hair shampoo compositions containing fatty acid lactylates or glycolates while the cleaning actions of these shampoos is satisfactory the foam remains minimal. In order to achieve higher foaming action it is described to incorporate booster surfactants, such as sodium lauryl sulphate or triethanol amine lauryl sulphate, in the shampoo compositions. However, these booster surfactants are causing a high degree of irritancy when applied on human skin.

WO 91/09923 describes compositions comprising an ultra mild surfactant and a foam enhancer. The ultra mild surfactant is an alkyl glyceryl ether sulfonate (AGS) which has a hydrophobic group containing a linear alkyl chain containing from about 7 to 9 carbon atoms. Conventional foam boosters such as amine oxides and water soluble halide salts are added to improve lather creaminess, volume and stability.

EP-A-224 796 (Kao) describes a detergent composition comprising (a) a phosphate surfactant and (b) an acyl lactylate having an acyl group containing 12 to 18 carbon atoms. Specific examples for such combinations are mixtures of lauryl phosphate and stearoyl lactylate, isostearoyl lactylate and lauroyl lactylate, respectively.

US-A-4, 761, 279 (Eastman Kodak) discloses shaving cream formulations comprising salts of C₁₄-C₂₂ acyl lactylates, saturated onoglycerides, propylene glycol monoesters and humectants .

It has now been discovered that a combination of specific short-chain surfactants with specific long-chain surfactants provides mild cleansing compositions with the added attribute that by using these compositions a high degree of lather is generated. Unexpectedly, these properties have been achieved by combining very mild surfactants, which on application on their own give unsatisfactory lather in terns of foam volume. The synergistic effect obtained by combining the specific short-chain and the specific long- chain surfactant is described later herein.

Definition of the Invention

Accordingly, the invention provides an aqueous cleansing composition, which comprises:

(a) a short-chain anionic surfactant chosen from C₆-C₉ alkyl ether sulphates, C₈-C_n acyl lactylates, C₆-C₉ acyl methyl taurates, C₆-C₉ acyl isethionates, C₆- C_u fatty acid soaps, C₆-C₉ alkyl sulphates, C₆- C_n acyl sarcosinates, C_b-C₉ alkyl sulphosuccinates, C₆-C₉ alkyl ether sulphosuccinates, or mixtures thereof;

(b) a long-chain anionic surfactant chosen from C₁₃-C₁₈ alkyl ether sulphates, C₁₃-C_lβ acyl lactylates, C₁₃- C₁₆ acyl methyl taurates, C₁₃-C₁₅ acyl isethionates, C₁₃-C₁₆ alkyl sulphates, C₁₃-C₁₆ acyl sarcosinates,

C₁₃-C₁₆ alkyl sulphosuccinates, C₁₃-C_lf alkyl ether sulphosuccinates, or mixtures thereof;

(c) optionally, a medium-chain anionic surfactant chosen from C₁₀-C₁₂ alkyl ether sulphates, C₁₂ acyl lactylates, C₁₀-C₁₂ acyl methyl taurates, C₁₀-C₁₂ acyl sethionates, C₁₀-C₁₂ alkyl sulphates, C₁₂ acyl sarcosinates, C₁₀-C₁₂ alkyl sulphosuccinates, C₁₀-C₁₂ alkyl ether sulphosuccinates, or mixtures thereof,

water;

wherein (i) at least one of the surfactants (a) and (b) is selected from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates and the acyl isethionates; o_r the short-chain anionic surfactant (a) is a C₆-C_n fatty ac d soap;

ii) if surfactant (c) is present, then the surfactants (a), (b) and (c) are present in an amount such that the weight ratio of (c) : [ (a) + (b) ] is less than 1:1.

Detailed Description of the Invention

Short-chain anionic surfactant (a)

The aqueous cleansing composition according to the invention comprises from 0.1 to 36% by weight of a short-chain surfactant chosen from C₆-C₉ alkyl ether sulphates, C₈-C_n acyl lactylates, C₆-C₉ acyl methyl taurates, C₆-C₉ acyl isethionates, C₆-C_n fatty acid soaps, C₆-C alkyl sulphates, C₆-C_u acyl sarcosinates, C₆-C₉ alkyl sulphosuccinates, C₆-C₉ alkyl ether sulphosuccinates, or mixtures thereof.

It is preferred to use the short-chain anionic surfactant (a) m amounts of from 0.5 to 20% preferably from 1 to 10% by weight m the cleansing composition according to the invention.

Lonσ-chain anionic surfactant (b)

The aqueous cleansing composition according to the invention comprises from 0.1 to 36% by weight of a long-chain surfactant chosen from chosen from C₁₃-C₁₈ alkyl ether sulphates, C₁₃-C₁₈ acyl lactylates, C₁₃-C₁₆ acyl methyl taurates, C₁₃-C₁₅ acyl isethionates, C₁₍-C_lt alkyl sulphates, C₁₃-C₁₆ acyl sarcosinates, C₁₃-C₁₆ alkyl sulphosuccinates, C₁₃-C₁₆ alkyl ether sulphosuccinates, or mixtures thereof.

It is preferred to use the long-chain anionic surfactant (b) in amounts of from 0.5 to 20%, preferably from 1 to 10%, by weight in the cleansing composition.

Combination of short-chain surfactants (a) and long-chain surfactants (b)

The aforementioned short-chain surfactants and long-chain surfactants are combined in such a way so that at least one is chosen from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates, the acyl isethionates and the C₆-C_n fatty acid soaps, as specified above.

This means that:

a C₆-C₉ alkyl ether sulphate is present as short chain surfactant o_r a C₁₃-C₁₈ alkyl ether sulphate is present as long chain surfactant, or:

a C₈-C_u acyl lactylate is present as short-chain surfactant or a C₁₃-C₁₈ acyl lactylate is present as long-chain surfactant, or:

a C₆-C₉ acyl methyl taurate is present as short chain surfactant or a C₁₃-C₁₆ acyl methyl taurate is present as long chain surfactant, or:

a C₆-C₉ acyl isethionate is present as short chain surfactant or a C₁₃-C₁₅ acyl isethionate is present as long chain surfactant, or: a C₆-C_n acyl sarcosinate is present as short chain surfactant or a C₁₃-C₁₆ acyl sarcosinate is present as long chain surfactant; o_r

a C₆-C_u fatty acid soap is present as short chain surfactant.

Surprisingly, it is not essential for the purposes of the invention that both types of surfactants, long and short- chain, are chosen from the same homologous series of surfactants.

The weight ratio of the short-chain surfactant (a) to the long chain surfactant (b) is preferably in the range of 1:10 to 10:1, more preferably 1:3 to 6:1 and most preferably 1:1 to 3:1.

Medium-chain anionic surfactant

The cleansing composition according to the invention optionally comprises a medium-chain anionic surfactant (c) chosen from C₁₀-C₁₂ alkyl ether sulphates, C₁₂ acyl lactylates, C₁₀-C₁₂ acyl methyl taurates, C₁₀-C₁₂ acyl isethionates, C₁₀-C₁₂ alkyl sulphates, C₁₂ acyl sarcosinates, C₁₀-C₁₂ alkyl sulphosuccinates, C₁₀-C₁₂ alkyl ether sulphosuccinates, or mixtures thereof.

Within each homologous series of surfactants, it has been found that the above mentioned medium-chain anionic surfactants (c) are the species which, of the particular series, generate the highest degree of lather according to the foam test, described herebelow. These medium-chain surfactants, on the other hand, have been found in general to be the most irritant surfactant within their respective homologous series. The medium-chain surfactant (c) exists for every homologous series of surfactants and its specific chain length or chain-length range can be determined by the foam test described herebelow.

For example, according to the foam test described below, the C₁₂ acyl sarcosinate, recited above as one of the medium- chain anionic surfactants (c), is the medium-chain length acyl sarcosinate. It is thus the one acyl sarcosinate generating the highest degree of lather, and is also the most irritant surfactant within the homologous series of acyl sarcosinates.

It is essential for the purposes of the present invention that the short-chain anionic surfactant (a) , the long-chain anionic surfactant (b) and the medium-chain anionic surfactant (c) are present in amounts such that the weight ratio of (c) : (a) + (b) is less than 1:1.

The amounts of the surfactants (a) , (b) and (c) are preferably chosen so that the weight ratio of (c) : (a) + (b) is less than 1:1.5 and more preferred less than 1:2. It is, however, most preferred that no medium-chain surfactant (c) is present in compositions according to the invention.

According to the teaching of the prior art high foaming compositions can only be obtained by using high foaming surfactants, in particular medium-chain surfactants, simultaneously having the disadvantage of being very skin irritant compounds. In contrast to this teaching, the present invention provides extremely mild and high lathering aqueous cleansing compositions by using very mild surfactants which when used singly do not give sufficient foam. It is surprising that by use of mild and low foaming surfactants compositions can be provided having about the same foaming properties but not the undesired skin irritancy as the medium-chain surfactant. Water

The composition according to the invention comprises water in an amount of from 60 to 99%, preferably 96 to 70%, most preferably 92 to 78% by weight based on total weight of the composition.

Use of the composition

The invention also provides the use as a cleanser for human skin and hair of an aqueous composition which comprises:

(a) a short-chain anionic surfactant chosen from C₆-C₉ alkyl ether sulphates, C₈-C_n acyl lactylates, C₆-C₉ acyl methyl taurates, C₆-C₉ acyl isethionates, C₆-

C_n fatty acid soaps, C₆-C₈ alkyl sulphates, C₆- C_n acyl sarcosinates, C₆-C₉ alkyl sulphosuccinates,

C₆-C₉ alkyl ether sulphosuccinates, or mixtures thereof;

(b) a long-chain anionic surfactant chosen from C₁₃-C₁₈ alkyl ether sulphates, C₁₍-C₁₈ acyl lactylates, C₁₃- C₁₆ acyl methyl taurates, C₁₃-C₁₅ acyl isethionates, C₁₃-C₁₆ alkyl sulphates, C₁₃-C_lb acyl sarcosinates, C₁₃-C₁₆ alkyl sulphosuccinates, C₁₃-C₁₆ alkyl ether sulphosuccinates, or mixtures thereof;

(c) optionally, a medium-chain anionic surfactant chosen from C₁₀-C₁₂ alkyl ether sulphates, C₁₂ acyl lactylates, C_ιn-C₁₂ acyl methyl taurates, C_ιn-C_ι: acyl isethionates, C₁₀-C₁₂ alkyl sulphates, C₁₂ acyl sarcosinates, C₁₀-C₁₂ alkyl sulphosuccinates, C^-C^ alkyl ether sulphosuccinates, or mixtures thereof, and (d) water;

wherein (i) at least one of the surfactants (a) and (b) is selected from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates and the acyl isethionates, o_r the short-chain anionic surfactant (a) is a C₆-C_n fatty acid soap;

(ii) if surfactant (c) is present, then the surfactants (a), (b) and (c) are present in an amount such that the weight ratio of (c) : [(a) +

(b) ] is less than 1:1.

Compositions of the invention may be formulated for washing the hair or skin, for example, hair shampoos; rinse-off hair care products; bath or shower gels; and facial washing compositions .

Preferably the compositions according to the invention will also include a cosurfactant . The cosurfactant can be selected from any known surfactant suitable for topical application to the human body and is selected from nonionic, zwitterionic and cationic surfactants and mixtures thereof. Mild surfactants, ie. surfactants which do not damage the stratum corneum, the outer layer of skin, are particularly preferred.

Suitable nonionic surface active agents include alkyl polysaccharides, lactobionamides, ethyleneglycol esters, glycerol monoethers, polyhydroxyamides (glucamide) , primary and secondary alcohol ethoxylates, especially the C₈_₂₀ aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol. Preferred zwitterionic detergents are those which have an alkyl or alkenyl group of 7 to 18 carbon atoms and comply with an overall structural formula:

O R^:

R -H-C-NH (CH₂)_m-]_n-N⁺-X-Y

R^J

where R¹ is alkyl or alkenyl of 7 to 18 carbon atoms R² and R³ are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 3 carbon atoms

m is 2 to 4 n is 0 or 1 X is alkylene of 1 to 3 carbon atoms optionally substituted with hydroxyl, and Y is -C0₂ ^~ or -SO/

Zwitterionic detergents within the above general formula include simple betaines of formula:

R

and amido betaines of formula:

R^"

where m is 2 or 3. In both formulae R¹ , R^'' and R³ are as defined previously. R¹ may, in particular, be a mixture of C₁₂ and C₁₄ alkyl groups derived from coconut so that at least half, preferably at least three quarters of the groups R¹ have 10 to 14 carbon atoms. R and R³ are preferably methyl.

A further possibility is a sulphobetaine of formula:

R²

R -N⁺- (CH₂)₃SO,^"

R³ or R¹

I

R'-CONHfCH.),. N⁺- (CH₂)₃S0₃ R³ where m is 2 or 3, or variants of these in which

-(CH₂)₃S0₃ is replaced by

OH

I

-CH,CHCH₂S0₃ R¹, R² and R³ in these formulae are as defined previously.

The compositions of the invention may comprise a structurant, i.e. a material added to increase the viscosity at low shear, such as less than Is^-1. Suitable materials include swelling clays, for example laponite; fatty acids and derivatives thereof and, in particular, fatty acid monoglyceride polyglycol ethers cross-linked polyacrylates such as Carbopol (TM) (polymers available from Goodrich) ; acrylates and copolymers thereof, polyvinylpyrrolidone and copolymers thereof; polyethylene imines; salts such as sodium chloride and ammonium sulphate; sucrose esters; gellants; and mixtures thereof.

Of the clays, particularly preferred are synthetic hectorite (laponite) clay used in conjunction with an electrolyte salt capable of causing the clay to thicken. Suitable electrolytes include alkali and alkaline earth salts such as halides, ammonium salts and sulphates.

The compositions according to the invention may also comprise a thickening agent, ie a material which maintains the viscosity of the composition as the shear rate thereof is increased during use. Suitable materials include cross- linked polyacrylates such as Carbopol (TM) (polymers available from Goodrich) ; fatty acids and derivatives thereof and, in particular, fatty acid monoglyceride polyglycol ethers; natural gums including alginates, guar, xanthan and polysaccharide derivatives including hydroxy ethyl cellulose, carboxy methyl cellulose and hydroxypropyl guar; propylene glycols and propylene glycol oleates; salts such as sodium chloride and ammonium sulphate; glycerol tallowates; and mixtures thereof.

Further examples of structurants and thickeners are given in the International Cosmetic Ingredient Dictionary, Fifth

Edition, 1993, published by CTFA (The Cosmetic, Toiletry & Fragrance Association), incorporated herein by reference.

Examples of other adjuncts which may be added to the compositions of the invention include opacifiers; preservatives such as para-hydroxy benzoate esters; antimicrobials such as antioxidants such as butyl hydroxy toulene; bactericides ; humectants such as glycerol and sorbitol; waxes; plant extracts such as Aloe Vera, witch hazel and elderflower; colourants; and perfumes. EXAMPLES

Surfactant blends having the compositions as defined for each Example/Comparative Example were evaluated for skin mildness and lather performance according to the following protocols :

Zein test (Skin irritancy)

The skin irritancies of the various formulations was measured by the so-called Zein test. This in-vitro test method makes use of the correlation between binding ability of surfactants to proteins to the damage the surfactant causes to the skin. The de-naturation of epidermal protein structures is a key mechanism in the development of observable damage to the skin by surfactants. Zein protein, an insoluble protein extracted from corn kernel, is used as a model for epidermal protein and the solubility of the Zein protein in surfactant solutions is a reliable guide for the skin irritancy caused by the surfactant. The test involves establishing the amount of Zein protein which can be solubilised by surfactant. 5g of Zein protein is dispersed in 40 cm3 of surfactant solution (at 2%) . The mixture is shaken for 1 hour at 35 deg C, and immediately centrifuged to remove any non-solubilised Zein. The amount solubilised is estimated from the solution nitrogen content using micro-Kjeldahl method (making allowance for any nitrogen in the surfactant).

Foam volume Test

In order to assess the foaming power of the compositions, the following test was used. 25 ml of the test solution containing 10% total surfactant in distilled water, and 0.5 g of artificial sebum, are added to a 250 ml measuring cylinder. The solution is agitated by means of a rubber bung attached to a rod. The rubber bung is modified so that it has a maximum diameter 5mm less than the internal dimensions of the cylinder. The bung is moved up and down inside the cylinder so that it passes through the solution and foam. The plunger is oscillated up and down twice per second. After 40 cycles the plunger is removed, and the volume of foam measured.

Example 1 and Comparative Examples A to C

Ether Sulphates

Comparative Example A is Linevol 79 Ether Sulphate 3EO (ex Shell) which is a blend of C7, C8 and C9 alkyl chains such that their alkyl chain length weight average is 8.2.

Comparative Example B is Dobanol 23 Ether Sulphate 3EO (ex Shell) which is a blend of C12 and C13 alkyl chains such that their alkyl chain length weight average is 12.5.

Comparative Example C is Dobanol 45 Ether Sulphate 3EO (ex Shell) which is a blend of C14 and C15 alkyl chains such that their alkyl chain length weight average is 14.5.

Example 1 is blend of Linevol 79 Ether Sulphate 3EO (ex Shell) and Dobanol 45 Ether Sulphate 3EO (ex Shell) such that their alkyl chain length weight average is 11.4. Foam volume Zein test

(ml) (%N₂)

Comp . Ex A 70 0.15

Comp . Ex . B 100 0.45

Comp . Ex . C 75 0.32

Ex 1 105 0.22

Thus showing that the blend of short and long chains (Ex 1) gives equivalent lather to the intermediate chains (Comp.Ex B) , but with a much lower Zein score.

Example 2 and Comparative Examples D and E

Soap and Ether Sulphate blended in the presence of Amidobetaine

Comparative Example D is 10% coco Ether Sulphate (3EO) [Empicol 0251 ex Albright and Wilson] + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt] .

Comparative Example E is 10% Sodium Caprylate soap + 5% coco amidobetaine.

Example 2 is 8% Coco Ether Sulphate (3EO) + 2% Sodium Caprylate soap + 5% coco amidobetaine.

Foam volume Zein test (ml) (%N₂)

Comp . . Ex.D 79 0.23

Comp. , Ex.E 51 0.30 Ex 2 145 0.24 Addition of the required amount of short chain soap in the blend of Example 2 has boosted lather without adversely affecting mildness (Zein) compared with a typical shampoo formulation such as is illustrated by Comparative Example D.

Example 3 and Comparative Examples F and G

Short chain Taurate and Ether sulphate blended in the presence of Amidobetaine.

Comparative Example F is 10% Coco Ether Sulphate (3EO) [Empicol 0251 ex Albright and Wilson] + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt] .

Comparative Example G is 10% C8 Taurate + 5% coco amidobetaine .

Example 3 is 7% Coco Ether Sulphate (3EO) + 3% C8 Taurate + 5% coco amidobetaine.

Foam volume Zein test

(ml) (%N₂)

Comp.Ex F 79 0.23

Comp.Ex G 44 0.24 Ex 3 145 0.24

Addition of the required amount of short chain Taurate in the blend of Example 3 has boosted lather without adversely affecting mildness (Zein) .

Example 4 and Comparative Examples H and I Short chain Isethionate and Ether sulphate blended in the presence of Amidobetaine

Comparative Example H is 10% Coco Ether Sulphate (3EO) [Empicol 0251 ex Albright and Wilson] + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt].

Comparative Example I is 10% C8/10 Isethionate [containing a blend of 42% C8, 45% CIO, 5% C16 5% C18] + 5% coco amidobetaine.

Example 4 is 6% Coco Ether Sulphate (3EO) + 4% C8/10 Isethionate + 5% coco amidobetaine.

Foam volume Zein test

(ml) (%N₂)

Com . Ex H 79 0, .23

Com . Ex I 80 0. .27

Ex 4 173 0. .25

Addition of the required amount of short chain Isethionate in the blend of Example 4 has boosted lather without adversely affecting mildness (Zein).

Example 5 and Comparative Examples J and K

Short chain Sarcosinate and Ether sulphate blended in the presence of Amidobetaine

Comparative Example J is 10% Coco Ether Sulphate (3EO)

[Empicol 0251 ex Albright and Wilson] + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt] . Comparative Example K is 10% C8 Sarcosinate + 5% coco amidobetaine .

Example 5 is 6% Coco Ether Sulphate (3EO) + 4% C8 Sarcosinate + 5% coco amidobetaine.

Foam volume Zein test (ml) (%N₂) Comp.Ex J 79 0. 23 Comp.Ex K 42 0. 30 Ex 5 111 0. 26

Addition of the required amount of short chain Sarcosinate in the blend of Example 5 has boosted lather without adversely affecting mildness (Zein) .

Example 6 and Comparative Examples L to N

Fatty Isethionates

Comparative Example L is Coco Isethionate which is a blend of C12, C14, C16 and C18 alkyl chains such that their alkyl chain length weight average is 13.1.

Comparative Example M is C8 Isethionate.

Comparative Example N is C14 Isethionate.

Example 6 is a blend of C8 Isethionate and C14 Isethionate. oam volume Zein test

(ml) (%N₂)

Comp . Ex L 88 0.42 Comp . Ex M 130 0.72 Comp . Ex N 0 0.50 Ex 6 124 0.45

Thus showing that the blend of short and long chains (Example 6) gives equivalent lather to the medium-length chains (Comp.Ex M) , but with a much lower Zein score.

Example 7 and Comparative Examples O and P

Soap and Coco Isethionate blended in the presence of Amidobetaine

Comparative Example 0 is 10% Coco Isethionate (average chain length C13.1) + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt] .

Comparative Example P is 10% Sodium Caprylate soap + 5% coco amidobetaine.

Example 7 is 7% Coco Isethionate + 7% Sodium Caprylate soap + 5% coco amidobetaine.

Foam vo _'lume Zein test

(ml) (%N₂)

Comp . Ex 0 110 0.23

Comp.Ex P 84 0.30

Ex 7 170 0.30 Addition of the required amount of short chain soap in the blend of Example 7 has boosted lather without adversely affecting mildness (Zein) .

Example 8 and Comparative Examples Q and R

Short chain Sarcosinate and Coco Isethionate blended in the presence of Amidobetaine

Comparative Example Q is 10% Coco Isethionate + 5% coco amidobetaine [Tegobetaine C ex Goldschmidt].

Comparative Example R is 10% C8 Sarcosinate + 5% coco amidobetaine .

Example 8 is 7% Coco Isethionate + 3% C8 Sarcosinate + 5% coco amidobetaine.

Foam volume Zein test (ml) ( %N₂ )

Comp.Ex Q 110 0 . 23

Comp.Ex R 44 0 . 30

Ex 8 140 0 . 27

Addition of the required amount of short chain Sarcosinate in the blend of Example 8 has boosted lather without adversely affecting mildness (Zein) .

Claims

1. An aqueous cleansing composition, which comprises:

(a) a short-chain anionic surfactant chosen from C₆-C₉ alkyl ether sulphates, Cς-Cn acyl lactylates, C₆-C₉ acyl methyl taurates, C_b-C₉ acyl isethionates, C₆- Cii fatty acid soaps, C_t--C₉ alkyl sulphates, C₆- Cii acyl sarcosinates, C_t-C₉ alkyl sulphosuccinates, C₆-C₉ alkyl ether sulphosuccinates, or mixtures thereof;

(b) a long-chain anionic surfactant chosen from C₁₃-C1₈ alkyl ether sulphates, Cι₃-Cιa acyl lactylates, C13- Ci₆ acyl methyl taurates, C13-C15 acyl isethionates,

Ci3-Cι_b alkyl sulphates, C -Cι_b acyl sarcosinates, C₁₃-C₁₆ alkyl sulphosuccinates, Cι₃-C₁₆ alkyl ether sulphosuccinates, or mixtures thereof;

(c) optionally, a medium-chain anionic surfactant chosen from C₁₀-C₁ alkyl ether sulphates, Cι_ acyl lactylates, C10-C1₂ acyl methyl taurates, Cι₀-Cι„ acyl isethionates, Cι₀-Cι₂ alkyl sulphates, d_ acyl sarcosinates, Cι₀-Cι₂ alkyl sulphosuccinates, C10-C1 alkyl ether sulphosuccinates, or mixtures thereof, and

(d) water;

wherein (i) at least one of the surfactants (a) and (b) is selected from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates and the acyl isethionates, o_r the short-chain anionic surfactant (a) is a C_b-Cn fatty acid soap;

(ii) if surfactant (c) is present, then the surfactants (a) , (b) and (c) are present in an amount such that the weight ratio of (c) : [(a) + (b) ] is less than 1:1.

2. A cleansing composition according to claim 1, in which the surfactants (a) , (b) and (c) are present in an amount such that the weight ratio of (c) : [ (a) + (b) ] is less than 1:1.5, preferably less than 1:2.

3. A cleansing composition according to claim 1 or claim 2, in which no medium-chain surfactant (c) is present.

4. A cleansing composition according to any one of claims 1 to 3 , in which the surfactant (a) is selected from the group consisting of C₈-Cι₀ acyl lactylates, C_b-C_P acyl methyl taurates, C₆-Cς acyl isethionates, C_e-C alkyl ether sulphates and C₈-Cιo acyl sarcosinates.

5. A cleansing composition according to any one of claims 1 to 4, in which the surfactant (b) is selected from the group consisting of C14-C1C, acyl lactylates, CI₄-CH acyl methyl taurates, C14-C16 acyl isethionates, C14-C16 alkyl ether sulphates, and Ci -C acyl sarcosinates.

6. A cleansing composition according to any one of claims 1 to 5, in which the short-chain surfactant (a) and the long- chain surfactant (b) are chosen from the same homologous series of surfactants.

7. A cleansing composition according to any one of claims 1 to 6, in which the weight ratio of surfactant (a) : (b) is in the range off 1:10 to 10:1, more preferably 1:3 to 6:1 and most preferably 1:1 to 3:1.

8. The use as a cleanser for human skin and hair of an aqueous composition which comprises:

(a) a short-chain anionic surfactant chosen from C₆-C₉ alkyl ether sulphates, C_f-Cn acyl lactylates, C₆-C₉ acyl methyl taurates, C_b-C₉ acyl isethionates, C₆~ Cii fatty acid soaps, C_b-C₉ alkyl sulphates, C₆- Cii acyl sarcosinates, C,.-C₃ alkyl sulphosuccinates, C₆-C₉ alkyl ether sulphosuccinates, or mixtures thereof;

(b) a long-chain anionic surfactant chosen from C13-C₁8 alkyl ether sulphates,

acyl lactylates, Cι₃- Ci6 acyl methyl taurates, C13-C15 acyl isethionates, Ci₃-Cι_b alkyl sulphates,

acyl sarcosinates,

C₁₃-C₁₆ alkyl sulphosuccinates, Ci -Cι_b alkyl ether sulphosuccinates, or mixtures thereof;

(c) optionally, a medium-chain anionic surfactant chosen from Cι₀-Cι₂ alkyl ether sulphates, C ₂ acyl lactylates, C₁₀-C₁₂ acyl methyl taurates, Cm-Cn acyl isethionates, Cι₀-Cι₂ alkyl sulphates, C_ι: acyl sarcosinates, C_αo-Cι₂ alkyl sulphosuccinates, C10-C1- alkyl ether sulphosuccinates, or mixtures thereof, and

water; wherein (i) at least one of the surfactants (a) and (b) is selected from the group consisting of the acyl lactylates, the acyl sarcosinates, the acyl methyl taurates, the alkyl ether sulphates and the acyl isethionates; o_r the short-chain anionic surfactant (a) is a Cc-Cn fatty acid soap;

(ii) if surfactant (c) is present, then the surfactants (a), (b) and (c) are present in an amount such that the weight ratio of (c) : [ (a) +

(b) ] is less than 1:1.