WO2025124889A1

WO2025124889A1 - Alkyl ether sulphate surfactant system for cleansing

Info

Publication number: WO2025124889A1
Application number: PCT/EP2024/083607
Authority: WO
Inventors: David Franck Frederic BROSSAULT; Jessica Lesley MCHUGH; Jules ORIOU; Pierre Starck
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Priority date: 2023-12-15
Filing date: 2024-11-26
Publication date: 2025-06-19
Anticipated expiration: 2026-06-15

Abstract

A cleansing composition comprising: a) from 5 to 20 wt % of a surfactant system consisting of: i) from 3 to 18 wt % of an anionic surfactant combination comprising a combination of alkyl ether sulphates that have the general formula (I) by weight of the total composition: R-O-(CH₂CH₂-O)_n-SO₃ ^-M⁺ (I) in which, R is selected from linear alkyl groups having from C8 to C14 carbon atoms and mixtures thereof; n is a number that represents the average degree of ethoxylation and ranges from 0.5 to 1.5; and M is a solubilizing cation; the combination of alkyl ether sulphates comprises, by weight of the anionic surfactant combination: - from 20 to 80 wt % of a first alkyl ether sulphate having a primary chain length of C12/C14, where R in general formula (I) comprises from 65 to 78 wt % of C12 chains, and 20 to 35 wt % of C14 chains, by weight of R; - from 0 to 80 wt %, of a second alkyl ether sulphate having a primary chain length selected from C10, wherein R comprises 100 % C10; - from 0 to 80 wt %, of a third alkyl ether sulphate having a primary chain length selected from C8, where R comprises 100 % C8; and wherein the total amount of second and third alkyl ether sulphates is from 20 to 80 wt %; and P0000231WO CPL 26 ii) from 1 to 10 wt %, of a co-surfactant selected from a zwitterionic or amphoteric surfactant, based on the weight of the total composition; b) from 0.1 to 3 wt %, by weight of the total composition, of a viscosity modifier, which is an inorganic electrolyte; c) from 50 to 98 wt % by weight water by weight of the total composition; wherein the ratio of anionic (i) to zwitterionic (ii) is from 1:1 to 9:1; and wherein the composition has a viscosity of from 2,000 to 100,000 mPa.s.

Description

ALKYL ETHER SULPHATE SURFACTANT SYSTEM FOR CLEANSING

Field of the Invention

The present invention is directed to mild cleansing compositions comprising a combination of alkyl ether sulphate surfactants. This invention has particular application in the field of personal care, especially hair care.

Background of the Invention

Consumers desire mild personal care products that are gentle on the hair. Many traditional cleansing surfactants are perceived as being harsh and some consumers believe they strip the hair of natural goodness.

The most commonly used alkyl chains for cleaning surfactants predominantly have carboncarbon lengths of 8 to 18 carbon atoms, with a dominance at 12 to 14 carbon atoms (sodium lauryl ether sulphate (SLES) ) and cocoamidopropyl betaine (CAPB) are traditional examples). These are defined only in even numbers as found in nature, although odd number chain lengths can be obtained from petrochemical sources. Natural materials can be synthesized from fatty acids extracted from vegetable triglyceride oils, most commonly palm kernel oil and coconut oil, which are the most common sources of C12 to C14 carbon chains. Most other vegetable oils have a lower content of chains of length below C16, and those that do (e.g. babassu oil and macauba oil) are not available commercially at an industrial scale. There is much current interest in moving away from a chain length distribution of C12 to C14.

The formation of an isotropic phase during manufacture of liquid cleansing formulations is known to produce products having high quality cleansing and foaming properties, along with ideal rheological properties for manufacturing and consumer use.

In the past, attempts have been made to provide high foaming, mild surfactants using mixtures of surfactants. Using petrochemically derived materials, US6001787 describes an aqueous cleansing composition, which consists of: (a) a short-chain anionic surfactant having 06 -09 chains; (b) a long-chain anionic surfactant having 013 -018 carbon chains; and (c) optionally, a medium-chain anionic surfactant having 010 -012 chains; at a ratio of (c):[(a) + (b)] of less than 1 :1 ; (d) a surfactant suitable for topical application to the human body selected from the group consisting of non ionic, zwitterionic and cationic surfactants, (e) a structurant; (f) a thickening agent and other adjuncts.

However, we have found that when you start mixing chain lengths, viscosity properties are severely compromised.

We have now found that a combination of surfactants having different chain lengths can be used in controlled amounts and at specific ratios of chain lengths to enable viscosity to be built, whilst also achieving a new mildness benefit and retaining the advantages of the traditional SLES based system, namely good cleaning, foaming and deposition. Advantageously, less salt and/or additional viscosity modifiers are required to achieve desired viscosity.

Summary of the Invention

In a first aspect, the invention provides a cleansing composition comprising: a) from 5 to 20 wt % of a surfactant system consisting of: i) from 3 to 18 wt % of an anionic surfactant combination comprising a combination of alkyl ether sulphates that have the general formula (I) by weight of the total composition:

R-O-(CH₂CH2-O)n-SO₃-M⁺ (I) in which, R is selected from linear alkyl groups having from C8 to C14 carbon atoms and mixtures thereof; n is a number that represents the average degree of ethoxylation and ranges from 0.5 to 1.5; and M is a solubilizing cation; the combination of alkyl ether sulphates comprises, by weight of the anionic surfactant combination:

- from 20 to 80 wt % of a first alkyl ether sulphate having a primary chain length of C12/C14, where R in general formula (I) comprises from 65 to 78 wt % of C12 chains, and 20 to 35 wt % of C14 chains, by weight of R; - from 0 to 80 wt %, of a second alkyl ether sulphate having a primary chain length selected from C10, wherein R comprises 100 % C10;

- from 0 to 80 wt %, of a third alkyl ether sulphate having a primary chain length selected from C8, where R comprises 100 % C8; and wherein the total amount of second and third alkyl ether sulphates is from 20 to 80 wt %; and ii) from 1 to 10 wt % of a co-surfactant selected from a zwitterionic or amphoteric surfactant, based on the weight of the total composition; b) from 0.1 to 3 wt %, by weight of the total composition, of a viscosity modifier, which is an inorganic electrolyte; c) water; wherein the weight ratio of anionic surfactant (i) to zwitterionic or amphoteric surfactant (ii) is from 1 :1 to 9: 1 ; and wherein the composition has a viscosity of from 2,000 to 100,000 mPa.s; when measured at 30 degrees C and 4s-7, using sandblasted 40mm parallel plates, on a Wingspan rheometer (TA instruments).

A second aspect of the invention provides a method of cleansing hair including the step of applying to the hair a composition of the first invention.

A use is provided, of the composition of the first aspect, to provide mild cleansing to hair. The use should provide milder cleansing than a similar composition that does not comprise the second and third alky ether sulphates as defined herein. The level of mildness is suitably determined using a Zein Protein Mildness method as described herein. Detailed of the Invention

Many raw materials contain, what are known in the industry as, carry-over ingredients. These are often used for example as processing aids, preservatives, emulsifiers, etc. These carry-over ingredients are present in very small quantities and perform a function for the raw material (for example as an emulsifier for a silicone). Carry-over ingredients are present in the full compositions at levels that are too low to have a material effect on the properties of the composition. They are not intended to be part of the invention.

The surfactant

The compositions of the invention comprise a surfactant system that consists of i) an anionic surfactant combination and ii) a zwitterionic and/or amphoteric co-surfactant.

The compositions of the invention are free from anionic surfactants and zwitterionic and amphoteric surfactants other than those defined in i) and ii).

In the context of this invention, by free from anionic, zwitterionic and amphoteric surfactants, other than those defined in i) and ii) means preferably the level of anionic, zwitterionic and amphoteric surfactants other than those defined in i) and ii) is less than 0.75 weight %, more preferably less than 0.5 weight %, more preferably less than 0.3 weight %, still more preferably less than 0.1 weight %, yet more preferably less than 0.01 weight %, still yet more preferably less than 0.001 weight %, and most preferably 0 weight % by weight of the total composition.

The surfactant system (a) is present in an amount of from 5 to 20 wt %, preferably 6 to 18 wt %, based on the weight of the total cleansing composition.

The anionic surfactant combination (i)

The anionic surfactant combination (i) comprises (and preferably consists of) a combination of alkyl ether sulphates that have the general formula (I):

R-O-(CH₂CH2-O)n-SO₃-M⁺ (I) in which, R is selected from linear alkyl groups having from C8 to C14 carbon atoms and mixtures thereof; n is a number that represents the average degree of ethoxylation and ranges from 0.5 to 1.4 preferably 0.75 to 1.25, more preferably from 0.8 to 1.2, most preferably 1 ; and M is a solubilizing cation.

The combination of alkyl ether sulphates comprises (and preferably consists of):

From 20 to 80 wt %, by wt of the anionic surfactant combination, of a first alkyl ether sulphate having a primary chain length of C12/C14. Preferably, the first alkyl ether sulphate is sodium lauryl ether sulphate (SLES). where R in general formula (I) comprises from 65 to 78 wt % of C12 chains, and 20 to 35 wt % %, preferably 22 to 35 wt % of C14 chains, by weight of R.

Other chains of different chain lengths (besides C12 and C14) may be present in minor amounts, for example from 0 to 4 wt %, or 0.001 to 4 wt %, such as 0.5 to 3 wt %, for example 2 wt %.

From 0 to 80 wt %, preferably 0 to 75 wt % of a second alkyl ether sulphate having a primary chain length selected from C10, wherein R comprises 100 % C10.

From 0 to 80 wt %, preferably 0 to 75 wt % of a third alkyl ether sulphate having a primary chain length selected from C8, where R comprises 100 % C8.

The total amount of second and third alkyl ether sulphates is from 20 to 80 wt %, preferably from 25 to 75 wt % by weight of the anionic surfactant combination.

Other chains may also be present, typically, from 0 to 4 wt % of C16 and from 0 to 0.5 wt %, for example 0.001 to 0.5 wt % of C18 chains. This is normally the case for naturally derived materials, which vary with the feedstock. The average degree of ethoxylation (n) of added ethylene oxide (EO) is from 0.5 to 1 .4, preferably 0.75 to 1.25, more preferably from 0.8 to 1.2, most preferably 1.

The anionic surfactant system is present in an amount of from 3 to 18 wt %, preferably 4 to 16 wt%, most preferably 6 to 14 wt %, by total weight of the composition.

The zwitterionic/amphoteric co-surfactant (ii)

Examples of suitable amphoteric and zwitterionic co-surfactants include alkyl amine oxides (for example lauryl amine oxide); alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines; alkyl amphoacetates (for example sodium cocoamphoacetate); alkyl amphopropionates, alkylamphoglycinates; alkyl amidopropyl hydroxysultaines; and mixtures thereof.

Preferably, the amphoteric or zwitterionic co-surfactant is selected from alkyl betaines, alkyl amidopropyl betaines, alkyl hydroxysultaines, alkyl amidopropyl hydroxy sultaines, and mixtures thereof.

Most preferred examples of amphoteric and zwitterionic surfactants for use in shampoos of the invention include lauryl betaine, cocamidopropyl betaine, lauryl hydroxysultaine, cocam idopropyl hydroxysultaine and mixtures thereof.

A particularly preferred amphoteric or zwitterionic co-surfactant is cocamidopropyl betaine.

The zwitterionic or amphoteric co-surfactant is present in an amount of from 1 to 10 wt %, preferably 1 .5 to 9 wt %, more preferably 2 to 9 wt %, based on the weight of the total composition.

Ratio of Anionic (i) : zwitterionic (ii)

The weight ratio of the anionic surfactant combination (i) to the zwitterionic/amphoteric cosurfactant (ii) is preferably 1 :1 to 9:1 , more preferably 1 :1 to 8:1. The viscosity modifier (b)

The viscosity modifier, for use in the compositions of the invention, is an inorganic electrolyte. Suitable inorganic electrolytes for use in the invention include metal chlorides (such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, zinc chloride, ferric chloride and aluminum chloride) and metal sulphates (such as sodium sulphate and magnesium sulphate). The inorganic electrolyte is used to provide viscosity to the composition.

Examples of preferred inorganic electrolytes for use in the invention include sodium chloride, potassium chloride, magnesium sulphate and mixtures thereof, most preferably sodium chloride.

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

The level of inorganic electrolyte in compositions of the invention ranges from 0.1 to 3%, preferably from 0.25 to 2.5% (by total weight of the composition).

The viscosity of the composition suitably ranges from 2,000 to 100,000 mPa.s, preferably from 2,000 to 50,000 mPa.s, more preferably from 2,100 to 40,000 mPa.s, when measured at 30 degrees C and 4s-7, using sandblasted 40mm parallel plates, on a Wingspan rheometer (TA instruments).

At these ranges our products are pourable yet thick enough to satisfy the consumer desire for thick compositions.

It is intended that the inorganic electrolyte is distinct from any inorganic electrolytes that may be present in the raw materials of the invention, as “carry over”.

Water (c)

The compositions of the invention are aqueous. The amount of water included in the compositions is such that the composition is 100 weight %. That is to say that water is added to “balance” the composition to 100 % weight.

The compositions of the invention will typically comprise greater than 50 wt % water, preferably 60 wt % water, more preferably greater than 70 %, still more preferably greater than 80 %, most preferably greater than 90 % water. The upper limit of water is determined by the amount of the other ingredients of the invention.

Thus the compositions of the invention comprise water in an amount of from 50 to an amount such that the total composition is 100 wt %.

Preferably the amount of water is 50 to 94.9, preferably 60 to 94 wt %, most preferably 80 to 90 wt % by weight of the total composition.

The following is a preferred method of making the compositions:

1 . A vessel is charged with water. Surfactants and any structurant are added with stirring.

2. The mixture is heated to about 30° C and mixed until homogenous.

3. When used, cationic polymer and silicone emulsion are then added and mixed well.

4. Preservative is added, if required.

5. The pH is adjusted to pH 4.5 using organic acid.

6. Salt is added to adjust the viscosity.

By combination, in the context of this invention, is meant that the first alkyl ether sulphate and the second alkyl ether surfactant may be mixed together before being used in the compositions of the invention or may be added separately to the compositions.

The Method

The invention provides a method of cleansing hair including the steps of applying to the hair, which is preferably wet, a composition of the first invention and rinsing the composition from the hair. The cleansing is milder compared to a similar comprising SLES as the anionic surfactant without a second and third alkyl ether chain as defined herein.

Mildness

The mildness is suitably measured using a Zein Protein Mildness test. This test enables the determination of the irritation potential (harshness) of a surfactant or a surfactant-based product (shower gel, shampoo, soap, washing-up liquid, etc.). Zein protein is a yellow corn protein that is similar to the keratin present in the skin and hair. Its physico-chemical characteristics are described in, for example, Metha, S.K. et al: "Significant effect of polar head group of surfactants on the solubilization of Zein in mixed micellar (SDS-DDAB) media"; Colloids and Surfaces 30 B: Biointerfaces 81 (2010) 74-80. The skin irritation potential and protein denaturation potential of the product is directly proportional to the quantity of dissolved proteins. Typically, the protein is first treated with dye and combined with an aqueous solution of the surfactant. The level of harshness of the surfactant is indicated by the amount of dye released such that a darker solution indicates a harsher composition. For example, as described in W02020002453A1 .

Free from polymeric thickeners

Preferably, the composition is free from polymeric thickeners.

In the context of this invention, by free from polymeric thickeners means preferably the level of polymeric thickeners is less than 0.75 weight %, more preferably less than 0.5 weight %, more preferably less than 0.3 weight %, still more preferably less than 0.1 weight %, yet more preferably less than 0.01 weight %, still yet more preferably less than 0.001 weight %, and most preferably 0 weight % by weight of the total composition.

Whilst many polymers, regardless of their intended function (such as wet feel polymers, deposition polymers, structurants and so on) may influence viscosity, they are used at such a level so as to cause minimal or no thickening. For example, preferably at 0.005 to less than 0.75 wt %, preferably 0.005 to 0.5 wt %, typically 0.2 wt %.

Cationic deposition polymers may be used in the shampoo compositions of the invention.

Suitable cationic deposition polymers may be homopolymers which are cationically substituted or may be formed from two or more types of monomers. The weight average (M_w) molecular weight of the polymers will generally be between 100 000 and 3 million daltons. The polymers will have cationic nitrogen containing groups such as quaternary ammonium or protonated amino groups, or a mixture thereof. If the molecular weight of the polymer is too low, then the conditioning effect is poor. If too high, then there may be problems of high extensional viscosity leading to stringiness of the composition when it is poured. The cationic nitrogen-containing group will generally be present as a substituent on a fraction of the total monomer units of the cationic deposition polymer. Thus when the polymer is not a homopolymer it can contain spacer non-cationic monomer units. Such polymers are described in the CTFA Cosmetic Ingredient Directory, 3rd edition. The ratio of the cationic to non-cationic monomer units is selected to give polymers having a cationic charge density in the required range, which is generally from 0.2 to 3.0 meq/gm. The cationic charge density of the polymer is suitably determined via the Kjeldahl method as described in the US Pharmacopoeia under chemical tests for nitrogen determination.

Suitable cationic deposition polymers include, for example, copolymers of vinyl monomers having cationic amine or quaternary ammonium functionalities with water soluble spacer monomers such as (meth)acrylamide, alkyl and dialkyl (meth)acrylamides, alkyl (meth)acrylate, vinyl caprolactone and vinyl pyrrolidine. The alkyl and dialkyl substituted monomers preferably have C1-C7 alkyl groups, more preferably C1-3 alkyl groups. Other suitable spacers include vinyl esters, vinyl alcohol, maleic anhydride, propylene glycol and ethylene glycol.

The cationic amines can be primary, secondary or tertiary amines, depending upon the particular species and the pH of the composition. In general, secondary and tertiary amines, especially tertiary, are preferred.

Amine substituted vinyl monomers and amines can be polymerised in the amine form and then converted to ammonium by quaternization.

The cationic deposition polymers can comprise mixtures of monomer units derived from amine- and/or quaternary ammonium-substituted monomer and/or compatible spacer monomers.

Preferred cationic deposition polymers are selected from cationic diallyl quaternary ammonium- containing polymers, mineral acid salts of amino-alkyl esters of homo-and co-polymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms, cationic polyacrylamides, cationic polysaccharide polymers and mixtures thereof.

Suitable (non-limiting examples of) cationic deposition polymers include: cationic diallyl quaternary ammonium-containing polymers including, for example, dimethyldiallylammonium chloride homopolymer and copolymers of acrylamide and dimethyldiallylammonium chloride, referred to in the industry (CTFA) as Polyquaternium 6 and Polyquaternium 7, respectively; mineral acid salts of amino-alkyl esters of homo-and co-polymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms, (as described in U.S. Patent 4,009,256); cationic polyacrylamides (as described in WO95/22311).

Other cationic deposition polymers that can be used include cationic polysaccharide polymers, such as cationic cellulose derivatives, cationic starch derivatives, and cationic guar gum derivatives.

Cationic polysaccharide polymers suitable for use in compositions for use in the invention include monomers of the formula:

A-O-[R-N⁺(R¹)(R²)(R³)X-], wherein: A is an anhydroglucose residual group, such as a starch or cellulose anhydroglucose residual. R is an alkylene, oxyalkylene, polyoxyalkylene, or hydroxyalkylene group, or combination thereof. R¹, R² and R³ independently represent alkyl, aryl, alkylaryl, arylalkyl, alkoxyalkyl, or alkoxyaryl groups, each group containing up to about 18 carbon atoms. The total number of carbon atoms for each cationic moiety (i.e. , the sum of carbon atoms in R¹, R² and R³) is preferably about 20 or less, and X is an anionic counterion.

Another type of cationic cellulose includes the polymeric quaternary ammonium salts of hydroxyethyl cellulose reacted with lauryl dimethyl ammonium-substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 24. These materials are available from the Amerchol Corporation, for instance under the tradename Polymer LM-200.

Other suitable cationic polysaccharide polymers include quaternary nitrogen-containing cellulose ethers (e.g. as described in U.S. Patent 3,962,418), and copolymers of etherified cellulose and starch (e.g. as described in U.S. Patent 3,958,581). Examples of such materials include the polymer LR and JR series from Dow, generally referred to in the industry (CTFA) as Polyquaternium 10. A particularly suitable type of cationic polysaccharide polymer that can be used is a cationic guar gum derivative, such as guar hydroxypropyltrimethylammonium chloride (commercially available from Rhodia in their JAGUAR trademark series). Examples of such materials are JAGUAR C13S, JAGUAR C14 and JAGUAR C17.

Mixtures of any of the above cationic deposition polymers may be used.

Cationic deposition polymer will generally be present in a shampoo composition for use in the invention at levels of from 0.01 to 5%, preferably from 0.02 to 1%, more preferably from 0.05 to 0.8% by total weight of cationic polymer based on the total weight of the composition.

A composition for use in the method and use of the invention preferably comprises a suspending agent. Suitable suspending agents are selected from polyacrylic acids, cross-linked polymers of acrylic acid, copolymers of acrylic acid with a hydrophobic monomer, copolymers of carboxylic acid-containing monomers and acrylic esters, cross-linked copolymers of acrylic acid and acrylate esters, heteropolysaccharide gums and crystalline long chain acyl derivatives and mixtures thereof. The long chain acyl derivative is desirably selected from ethylene glycol stearate, alkanolamides of fatty acids having from 16 to 22 carbon atoms and mixtures thereof. Ethylene glycol distearate and polyethylene glycol 3 distearate are preferred long chain acyl derivatives, since these impart pearlescence to the composition. Polyacrylic acid is available commercially as Carbopol 420, Carbopol 488 or Carbopol 493. Polymers of acrylic acid crosslinked with a polyfunctional agent may also be used; they are available commercially as Carbopol 910, Carbopol 934, Carbopol 941 and Carbopol 980. An example of a suitable copolymer of a carboxylic acid containing monomer and acrylic acid esters is Carbopol 1342. All Carbopol (trademark) materials are available from Goodrich.

Suitable cross-linked polymers of acrylic acid and acrylate esters are Pemulen TR1 or Pemulen TR2. A suitable heteropolysaccharide gum is xanthan gum, for example that available as Kelzan mu.

Mixtures of any of the above suspending agents may be used. Preferred is a mixture of crosslinked polymer of acrylic acid and crystalline long chain acyl derivative.

Suspending agent will generally be present in a shampoo composition for use in the method and use of the invention at levels of from 0.1 to 10%, preferably from 0.1 to 5%, more preferably from 0.1 to 3% by total weight of suspending agent based on the total weight of the composition. Compositions for use in the method of the invention will preferably also contain one or more emulsified silicones, for enhancing conditioning performance.

The emulsified silicone is preferably selected from the group consisting of polydiorganosiloxanes, silicone gums, amino functional silicones and mixtures thereof.

Suitable silicones include polydiorganosiloxanes, in particular polydimethylsiloxanes which have the CTFA designation dimethicone. Also suitable for use in compositions for use in the method of the invention (particularly shampoos and conditioners) are polydimethyl siloxanes having hydroxyl end groups, which have the CTFA designation dimethiconol. Also suitable are silicone gums having a slight degree of cross-linking, as are described for example in WO 96/31188.

The viscosity of the emulsified silicone itself (not the emulsion or the final hair conditioning composition) is typically at least 10,000 cst at 25 °C the viscosity of the silicone itself is preferably at least 60,000 cst, most preferably at least 500,000 cst, ideally at least 1 ,000,000 cst. Preferably the viscosity does not exceed 10⁹ cst for ease of formulation.

Emulsified silicones for use in the shampoo compositions will typically have a D90 silicone droplet size in the composition of less than 30, preferably less than 20, more preferably less than 10 micron, ideally from 0.01 to 1 micron. Silicone emulsions having an average silicone droplet size (D50) of 0.15 micron are generally termed microemulsions.

Silicone particle size may be measured by means of a laser light scattering technique, for example using a 2600D Particle Sizer from Malvern Instruments.

Examples of suitable pre-formed emulsions include Xiameter MEM 1785 and microemulsion DC2-1865 available from Dow Corning. These are emulsions /microemulsions of dimethiconol. Cross-linked silicone gums are also available in a pre-emulsified form, which is advantageous for ease of formulation.

A further preferred class of silicones for inclusion in shampoos and conditioners of the invention are amino functional silicones. By "amino functional silicone" is meant a silicone containing at least one primary, secondary or tertiary amine group, or a quaternary ammonium group. Examples of suitable amino functional silicones include: polysiloxanes having the CTFA designation "amodimethicone". Specific examples of amino functional silicones suitable for use in the invention are the aminosilicone oils DC2-8220, DC2-8166 and DC2-8566 (all ex Dow Corning).

Suitable quaternary silicone polymers are described in EP-A-0 530 974. A preferred quaternary silicone polymer is K3474, ex Goldschmidt.

Also suitable are emulsions of amino functional silicone oils with non ionic and/or cationic surfactant.

Pre-formed emulsions of amino functional silicone are also available from suppliers of silicone oils such as Dow Corning and General Electric. Specific examples include DC939 Cationic Emulsion and the non-ionic emulsions DC2-7224, DC2-8467, DC2-8177 and DC2-8154 (all ex Dow Corning).

The total amount of silicone emulsion is from 0.01 wt% to 10 wt% of the total composition preferably from 0.1 wt% to 5 wt%, more preferably 0.5 wt% to 3 wt% is a suitable level.

The compositions for use in the method and use of the invention preferably comprise a preservative. A preferred preservative is sodium benzoate.

Where present, the preservative is preferably present in an amount of from 0.01 to 2 wt %, more preferably 0.01 to 1 wt %, most preferably 0.1 to 1 wt %, by total weight of the composition.

Other Ingredients

A composition of the invention may contain further optional ingredients to enhance performance and/or consumer acceptability. Examples of such ingredients include, for example, fragrance, dyes and pigments, pH adjusting agents (for examples organic acids, sodium hydroxide), pearlescers, opacifiers, preservatives, antimicrobials, structurants, solvents, feel modifying polymers. 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). The composition of the invention is primarily intended for topical application to the hair and scalp.

Most preferably the composition of the invention is topically applied to the hair and then massaged into the hair and scalp. The composition is then rinsed off the hair and scalp with water. Preferably the hair is then dried.

All amounts herein are by weight of the total composition, unless otherwise stated.

The invention will be further illustrated by the following, non-limiting Examples.

Examples

Building viscosity through salt-thickening and mildness are formulation properties which mostly depend on surfactant ingredients. Therefore, the following examples correspond to either simple formulations containing only surfactants and preservatives, or more complex formulations containing conditioning and structuring agents.

Each of the Tables below contain compositions at a comparable total surfactant (anionic + amphoteric) concentration. However, the example compositions where part of the SLES has been replaced by a shorter chain alkyl ether sulfate (AES) will show a slightly lower total surfactant value. This is to account for the difference in molecular weight between the materials, and enable a fair comparison of their properties based on comparable number of molecules in the formulation rather than comparable added weight of material. This is referred to herein as “molar matching”.

Preparation of compositions

All the shampoos were prepared using the following method:

1. A vessel was charged with water. Surfactants and any structurant were added with stirring.

2. The mixture was heated to 30° C and mixed until homogenous.

3. When used, cationic polymer and silicone emulsion were then added and mixed well.

4. Any preservative was added.

5. The pH was adjusted to pH 4.5 using citric acid. 6. Salt was then added to adjust the viscosity.

Measurement of Mildness

Mildness was measured using the Zein Protein Mildness test as described above. All values are based on 12 measurements and averages and standard deviations are reported. The statistical significance of the difference observed between the mildness data was assessed using the

'-Kramer

Viscosity was measured at 30 degrees C and 4s-7, using sandblasted 40mm parallel plates, on a Wingspan rheometer (TA instruments).

1 and 2, in accordance with the invention and

Materials used:

C12/C14 - Sodium Lauryl Ether Sulphate (SLES). Widely commercially available.

C8 Sodium Octyl Ether Sulpate

C10 - Sodium Decyl Ether Sulphate

C8/C10 mixture

C8 and C10 materials can be obtained from specialist suppliers using traditional synthesis methods on refined feedstocks (fatty alcohol with the reguired narrow chain length distribution).

Rinse-off agueous hair cleansing shampoo formulations were prepared, having different chain length content.

Table 1 : Compositions of Examples 1 and 2, in accordance with the invention and Comparative Example A, viscosity and protein mildness.

Fixed total surfactant: 13.6 wt%

Fixed anionic/amphoteric ratio: 4:1 C8, C10 and C8/C10 enrichment were molar matched to SLES, as explained above. Example 2: Examples 3 to 5, in accordance with the invention and Comparative Examples B to D

Rinse-off aqueous hair cleansing shampoo formulations were prepared, having different chain length content.

Table 2: Compositions of Examples 3 to 5, in accordance with the invention and

Comparative Examples B to D, viscosity and protein mildness.

Tukey-Kramer analysis, showed that the mildness results were significantly different between examples 3, 4 & 5 compared with B, C & D respectively. 3 different total surfactants (6wt%, 13.6wt% and 18wt%) Fixed anionic/amphoteric ratio (1:1)

Equivalent C10 enrichment is molar matched to SLES

Example 3: Examples 6 to 7, in accordance with the invention and Comparative Examples E to F

Table 3: Compositions of Examples 6 to 7, in accordance with the invention and Comparative Examples E to F, viscosity and protein mildness.

*Not measured because the viscosity was too high (gel-like) Tukey-Kramer analysis, showed that the mildness results were significantly different between the inventive and comparative examples.

Fixed 18 wt% total surfactant

Fixed anionic/amphoteric ratio (1:1)

C8 and C10 (Molar matched to SLES)

Claims

1. A cleansing composition comprising: a) from 5 to 20 wt % of a surfactant system consisting of: i) from 3 to 18 wt % by weight of the total compositiomof an anionic surfactant combination comprising a combination of alkyl ether sulphates that have the general formula (I)

R-O-(CH₂CH2-O)n-SO₃-M⁺ (I) in which, R is selected from linear alkyl groups having from C8 to C14 carbon atoms and mixtures thereof; n is a number that represents the average degree of ethoxylation and ranges from 0.5 to 1.4; and M is a solubilizing cation; the combination of alkyl ether sulphates comprises, by weight of the anionic surfactant combination:

- from 20 to 80 wt % of a first alkyl ether sulphate having a primary chain length of C12/C14, where R in general formula (I) comprises from 65 to 78 wt % of C12 chains, and 20 to 35 wt % of C14 chains, by weight of R;

- from 0 to 80 wt %, of a second alkyl ether sulphate having a primary chain length selected from C10, wherein R comprises 100 % C10;

- from 0 to 80 wt %, of a third alkyl ether sulphate having a primary chain length selected from C8, where R comprises 100 % C8; and wherein the total amount of second and third alkyl ether sulphates is from 20 to 80 wt %; and ii) from 1 to 10 wt %, of a co-surfactant selected from a zwitterionic or amphoteric surfactant, based on the weight of the total composition; b) from 0.1 to 3 wt %, by weight of the total composition, of a viscosity modifier, which is an inorganic electrolyte; c) water; wherein the ratio of anionic (i) to zwitterionic (ii) is from 1:1 to 9:1 ; and wherein the composition has a viscosity of from 2,000 to 100,000 mPa.s; when measured at 30 degrees C and 4s-7, using sandblasted 40mm parallel plates, on a Wingspan rheometer (TA instruments).

2. A composition as claimed in any preceding claim, wherein the second alkyl ether sulphate is present at a level of 0 to 75 wt %.

3. A composition as claimed in any preceding claim, wherein the third alkyl ether sulphate is present at a level of 0 to 75 wt %.

4. A composition as claimed in any preceding claim, wherein the total amount of second alkyl ether sulphate and third alkyl ether sulphate is from 25 to 75 wt %.

5. A composition as claimed in any preceding claim, wherein the zwitterionic or amphoteric surfactant is, selected from alkyl betaines, alkyl amidopropyl betaines, alkyl hydroxysultaines, alkyl amidopropyl hydroxy sultaines, and mixtures thereof.

6. A composition as claimed in claim 5, wherein the zwitterionic or amphoteric surfactant is, selected from lauryl betaine, cocamidopropyl betaine, lauryl hydroxysultaine, cocam idopropyl hydroxysultaine and mixtures thereof, preferably cocamidopropyl betaine.

7. A composition as claimed in any preceding claim, wherein the weight ratio of the anionic surfactant combination (i) to the zwitterionic/amphoteric co-surfactant (ii) is 1 :1 to 8:1.

8. A composition as claimed in any preceding claim, wherein the viscosity modifier is selected from sodium chloride, potassium chloride, magnesium sulphate and mixtures thereof, most preferably sodium chloride.

9. A composition according to any preceding claim, which is free from polymeric thickeners, whereinthe level of polymeric thickeners is less than 0.75 weight %, more preferably less than 0.5 weight %, more preferably less than 0.3 weight %, still more preferably less than 0.1 weight %, by weight of the total composition.

10. A composition according to any preceding claim, which further comprises a silicone in an amount of 0.5 to 6.5 wt %.

11. A method of treating hair comprising the step of applying to hair a composition as defined in any one of claims 1 to 10.

12. A use of the composition as defined in any one of claims 1 to 10, to provide mild cleansing to hair.