WO2017085025A1

WO2017085025A1 - Personal cleansing compositions

Info

Publication number: WO2017085025A1
Application number: PCT/EP2016/077607
Authority: WO
Inventors: Ningning LI; Joseph Muscat; Neil Scott Shaw; Sally Elizabeth WOOD
Original assignee: Unilever Plc; Unilever N.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2015-11-19
Filing date: 2016-11-14
Publication date: 2017-05-26

Abstract

The invention provides a personal cleansing composition with a pH below 5.1, the composition having an aqueous continuous phase including cleansing surfactant; and an oil phase including at least one oily liquid conditioning agent for skin and/or hair; in which the oily liquid conditioning agent is solubilised in wormlike micelles in the aqueous continuous phase via the incorporation of at least one inorganic electrolyte and at least one linker molecule which is selected from organic carboxylic acids of general formula (I): R(COOH) (I) in which R is an aromatic hydrocarbyl group having from 6 to 10 carbon atoms; and in which the level of the oily liquid conditioning agent in the composition ranges from 0.45 to 3% by weight based on the total weight of the composition.

Description

PERSONAL CLEANSING COMPOSITIONS

Field of the Invention

The present invention relates to personal cleansing compositions such as liquid soaps, body washes and shampoos.

Background and Prior Art

In order to provide skin and/or hair conditioning benefits in a cleansing base such as a liquid soap, body wash or shampoo, it has been proposed to include beneficial oils. Oils can confer a number of skin benefits to personal washing products, which include improvements in after-wash tightness, dryness, irritancy, moisturisation and skin feel. Oils can also act as a non-greasy lubricant for hair, help in detangling hair, and can form a barrier on the hair surface to protect the cuticle and create a smooth, fly-away free look.

Since shampoo is a "rinse-off" product, the level of oil deposited on hair can be low. However, incorporation of higher levels of oil into the product is not always possible since it may lower the viscosity and disrupt the product microstructure, resulting in undesirable phase separation.

The present invention addresses this problem.

Summary of the Invention

The present invention provides a personal cleansing composition with a pH below 5.1 , the composition having an aqueous continuous phase including cleansing surfactant; and an oil phase including at least one oily liquid conditioning agent for skin and/or hair; in which the oily liquid conditioning agent is solubilised in wormlike micelles in the aqueous continuous phase via the incorporation of at least one inorganic electrolyte and at least one linker molecule which is selected from organic carboxylic acids of general formula (I):

R(COOH) (I) in which R is an aromatic hydrocarbyl group having from 6 to 10 carbon atoms; and in which the level of the oily liquid conditioning agent in the composition ranges from 0.45 to 3% by weight based on the total weight of the composition. Detailed Description and Preferred Embodiments

For the purposes of the present invention, "aqueous continuous phase" means a continuous phase which has water as its basis. Suitably, the composition of the invention will comprise from about 50 to about 90%, preferably from about 55 to about 85%, more preferably from about 60 to about 85%, most preferably from about 65 to about 83% water (by weight based on the total weight of the composition). The cleansing surfactant may suitably be selected from one or more anionic surfactants.

Typical anionic surfactants for use as cleansing surfactants in the invention include those surface active agents which contain an organic hydrophobic group with from 8 to 14 carbon atoms, preferably from 10 to 14 carbon atoms in their molecular structure; and at least one water-solubilising group which is preferably selected from sulphate, sulphonate, sarcosinate and isethionate. Specific examples of such anionic surfactants include ammonium lauryl sulphate, ammonium laureth sulphate, trimethylamine lauryl sulphate, trimethylamine laureth sulphate, triethanolamine lauryl sulphate, trimethylethanolamine laureth sulphate, monoethanolamine lauryl sulphate, monoethanolamine laureth sulphate, diethanolamine lauryl sulphate, diethanolamine laureth sulphate, lauric monoglyceride sodium sulphate, sodium lauryl sulphate, sodium laureth sulphate, potassium lauryl sulphate, potassium laureth sulphate, sodium lauryl sarcosinate, sodium lauroyi sarcosinate, lauryl sarcosine, ammonium cocoyi sulphate, ammonium lauroyi sulphate, sodium cocoyi sulphate, sodium lauryl sulphate, potassium cocoyi sulphate, potassium lauryl sulphate, monoethanolamine cocoyi sulphate, monoethanolamine lauryl sulphate, sodium tridecyl benzene sulphonate, sodium dodecyl benzene sulphonate, sodium cocoyi isethionate and mixtures thereof.

A preferred class of anionic surfactants for use as cleansing surfactants in the invention are alkyl ether sulphates of general formula: R-0-(CH₂CH2-0)n-S0₃-M⁺ in which R is a straight or branched chain alkyl group having 10 to 14 carbon atoms, n is a number that represents the average degree of ethoxylation and ranges from 1 to 5, preferably from 2 to 3.5, and M is a alkali metal, ammonium or alkanolammonium cation, preferably sodium, potassium, monoethanolammonium or triethanolammonium, or a mixture thereof.

Specific examples of such preferred anionic surfactants include the sodium, potassium, ammonium or ethanolamine salts of Cio to C12 alkyl sulphates and Cio to C12 alkyl ether sulphates (for example sodium lauryl ether sulphate),

Mixtures of any of the above described materials may also be used. In a typical composition according to the invention the level of cleansing surfactant will generally range from 5 to 26% (by weight based on the total weight of the composition).

For the purposes of the present invention, the term "oil" means a non-aqueous compound which is immiscible with water (distilled or equivalent) at a concentration of 0.1wt%, at 25°C. The term "oily liquid" means an oil that is capable of flowing under its own weight under ambient conditions (1 atmosphere, 25°C).

Oily liquid conditioning agents suitable for use in the invention will generally

have a kinematic viscosity at 40°C of 100,000 cS (mm².s^"1) or less, preferably 50,000 cS (mm².s^"1) or less, more preferably 5,000 cS (mm².s^"1) or less.

Suitable oily liquid conditioning agents for use in the invention may generally be selected from cosmetically acceptable oils such as silicone oils, hydrocarbon-based oils and mixtures thereof.

For the purposes of the present invention, the term "silicone oil" means an oil which contains at least one silicon atom, and more particularly at least one Si-0 group. The term "hydrocarbon-based oil" means an oil formed from carbon and hydrogen atoms, and optionally oxygen and nitrogen atoms, and not containing any silicon or fluorine atoms. It may contain alcohol, ester, ether, carboxylic acid, amine and/or amide groups. These oils may be of plant, mineral or synthetic origin.

Examples of suitable silicone oils for use in the invention include linear or cyclic silicone oils having a kinematic viscosity of from about 0.65 to about 50, preferably from about 1 .5 to about 5 cS (mm².s^"1) at 25° C. Example of such materials include linear or cyclic polydimethylsiloxanes having from 2 to 7 siloxane units, such as

octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,

dodecamethylcyclohexasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane and their mixtures. Preferred are linear polydimethylsiloxanes having from 3 to 5 siloxane units and their mixtures. Such materials are commercially available for example as Dow Corning ® 200 series fluids. Preferred oily liquid conditioning agents for use in the invention are generally selected from hydrocarbon-based oils.

Examples of suitable hydrocarbon-based oils for use in the invention include oily liquid hydrocarbons such as C4-C50 straight or branched chain, saturated or unsaturated aliphatic or cycloaliphatic hydrocarbons and mixtures thereof. Straight chain

hydrocarbons will preferably contain from about 12 to about 30 carbon atoms. Branched chain hydrocarbons can and typically may contain higher numbers of carbon atoms. Also suitable are polymeric hydrocarbons, such as polymers of C2-6 alkenyl monomers (e.g. polyisobutene, polybutene) and poly oolefin oils derived from 1-alkene monomers having from about 6 to about 16 carbons, preferably from about 6 to about 12 carbon atoms (e.g. polymers derived from 1-octene, 1-decene, 1 -dodecene, 1- tetradecene, 1-hexadecene, and mixtures thereof). Polymeric hydrocarbons for use in the invention can be straight or branched chain polymers, and may be hydrogenated. The number average molecular weight of such polymeric materials can vary widely, but will typically range from about 200 up to about 3000.

Preferred oily liquid hydrocarbons for use in the invention include the various grades of mineral oil, and especially light mineral oil. Mineral oils are clear oily liquids obtained from petroleum oil, from which waxes have been removed, and the more volatile fractions removed by distillation. The fraction distilling between 250°C to 300°C is termed mineral oil, and it consists of a mixture of hydrocarbons, in which the number of carbon atoms per hydrocarbon molecule generally ranges from C10 to C40. The mineral oil may be characterised in terms of its viscosity, where light mineral oil is less viscous than heavy mineral oil. A suitable light mineral oil will generally have a kinematic viscosity of 3.9 to 5.0 cS (mm².s^"1) at 40°C and a specific gravity of 0.810 to 0.830 at 25°C. Such materials are commercially available under the brand name Lytol®. Other suitable hydrocarbon-based oils for use in the invention include oily liquid esters. Oily liquid esters for use in the invention are generally characterised by having at least 10 carbon atoms, and may be either straight-chained or branched. The esters may have hydrocarbyl chains derived from fatty acids or alcohols (e.g. monoesters, polyhydric alcohol esters, and di- and tri-carboxylic acid esters). The hydrocarbyl radicals may include or have covalently bonded thereto other compatible functionalities, such as amides and alkoxy moieties, such as ethoxy or ether linkages.

Examples of oily liquid esters for use in the invention include: aliphatic monohydric alcohol esters such as C5-C22 straight or branched-chain, saturated or unsaturated alkyl esters of C1-C18 straight or branched-chain, saturated or unsaturated alkyl alcohols (provided that the total number of carbon atoms in the ester is at least 10), such as isostearyl palmitate, isononyl isononanoate, myristyl propionate, isopropyl isostearate, isopropyl myristate, isopropyl palmitate, ethylhexyl palmitate, cetyl acetate, cetyl propionate, cetyl stearate, isodecyl neopentanoate, cetyl octanoate, isocetyl stearate , ethylhexyl stearate and mixtures thereof; aliphatic polyhydric alcohol esters such as C5-C22 straight or branched-chain, saturated or unsaturated alkyl esters of C3-C30 straight or branched-chain, saturated or unsaturated polyols (provided that the total number of carbon atoms in the ester is at least 10), such as propylene glycol dipelargonate, pentaerythrityl tetraoctanoate, trimethylolpropane tricaprylate/tricaprate, trioctanoin, pentaerythrityl tetrapelargonate, sorbitan trioleate, caprylic/capric triglyceride, neopentyl alcohol tetraoctanoate, and mixtures thereof; aliphatic polycarboxylic acid polyesters such as C5-C22 straight or branched-chain, saturated or unsaturated alkyl diesters of C2-C10 straight or branched-chain, saturated or unsaturated dicarboxylic acids (provided that the total number of carbon atoms in the ester is at least 10), such as diisopropyl adipate, dioctyl sebacate, dioctyl succinate, dioctyl maleate, diisostearyl adipate, diethyl sebacate, diisostearyl fumarate, dioctyl adipate and mixtures thereof; and/or C5-C22 straight or branched-chain, saturated or unsaturated alkyl triesters of C6-C10 straight or branched-chain, saturated or unsaturated tricarboxylic acids (provided that the total number of carbon atoms in the ester is at least 10), such as trioctyldodecyl citrate, triisostearyl citrate, triisopropyl citrate and mixtures thereof; and aliphatic esters of aromatic acids such as C12-C15 branched or unsaturated alkyl esters of benzoic acid.

Preferred oily liquid esters for use in the invention may be selected from the aliphatic monohydric and/or polyhydric alcohol esters which are described in more detail above.

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

The level of oily liquid conditioning agent (as defined above) in compositions of the invention depends on the particular material (s) used, but generally ranges from about 0.5 to about 3% by weight based on the total weight of the composition.

In a preferred composition according to the invention the oily liquid conditioning agent is selected from oily liquid hydrocarbons, oily liquid esters and mixtures thereof, at a level ranging from about 0.5 to about 1 .5%, more preferably from about 0.8 to about 1.2% (by weight based on the total weight of the composition).

The oily liquid conditioning agent is solubilised in wormlike micelles in the aqueous continuous phase.

"Wormlike micelles" in the context of this invention are elongated and flexible aggregates formed by the self-assembly of surfactant molecules in water. Above a threshold concentration, wormlike micelles entangle into a transient network, reminiscent of polymer solutions, and display viscoelastic properties. However, unlike a covalently bonded polymer backbone, the micelles are in a state of thermodynamic equilibrium with the solvent and are perpetually broken and reformed under Brownian fluctuations. This leads to a broad and dynamic distribution of micelle lengths which can change under an imposed shear or extensional flow. Wormlike micelles can be fully described by a number of structural parameters, which cover a broad range of length-scales. The overall length of the micelles is referred to as the contour length L and varies between a few (e.g. about 1 to 10) nanometers up to a few (e.g. about 1 or 2) microns. Cryo-TEM provides a direct visualization of the micelles and can be used to estimate the contour length, while light and neutron scattering give a more accurate determination. Radii of wormlike micelles are typically a few (e.g. about 1 to 10) nm. Another key structural parameter in the description of wormlike micelles is the persistence length /_p, the length over which the micelles are considered rigid. Although wormlike micelles can be extremely flexible and micrometres long, their large cross- section implies that on smaller length-scales (of order /_p ) they act as rigid rods.

Techniques such as rheology, light and neutron scattering and flow birefringence have been employed to estimate /_p, as well as simulations. Experimentally, persistence lengths from about 10 to about 40 nm have been reported in neutral systems. For charged wormlike micelles, the persistence length varies significantly with surfactant structure, counter-ion and salt concentration, but is typically a few tens of nanometers (e.g about 30 to about 100 nm).

The oily liquid conditioning agent is solubilised in wormlike micelles in the aqueous continuous phase via the incorporation of at least one inorganic electrolyte and at least one linker molecule as defined above.

"Linker molecules" in the context of this invention are chemical additives used in surfactant systems that enhance the surfactant-oil or surfactant-water interactions.

Lipophilic linkers segregate near the oil side of the interface close to the tails of the surfactants. The presence of the lipophilic linker extends the impact of the surfactant deeper into the oil phase and may promote additional orientation of the oil molecules. Hydrophilic linkers are surfactant-like molecules that coadsorb with the surfactant at the oil/water interface, but have a minimal interaction with the oil molecules. The adsorption of the hydrophilic linker at the oil/water interface increases the total interfacial area.

In general formula (I) above, R is preferably an aromatic hydrocarbyl ring having 6 carbon atoms.

An example of a preferred linker molecule for use in the invention is benzoic acid. The level of linker molecule of general formula (I) above in compositions of the invention preferably ranges from about 0.01 to about 1 % , more preferably from about 0.02 to about 0.5% by weight based on the total weight of the composition. The weight ratio of solubilised oily liquid conditioning agent (as defined above) to linker molecule of general formula (I) above in compositions of the invention generally ranges from about 15:1 to about 1 :1 , preferably from about 6:1 to about 1 :1 .

A particularly preferred composition according to the invention comprises sodium benzoate as the linker molecule of general formula (I), in combination with light mineral oil (as defined above) as the solubilised oily liquid conditioning agent, in the amounts and ratios given above.

Advantageously, the composition of the invention forms a microemulsion which is stable to phase separation without requiring the incorporation of any further linker molecules in addition to the linker molecule of general formula (I) which is described above.

Accordingly, the composition of the invention may suitably be substantially free of further linker molecules selected from phthalic acid, citric acid, mono- or dicarboxylic acids of formula Y-CH₂(CH₂)m -COOI-l , in which Y is selected from -H and -COOH and m is an integer ranging from 4 to 12, more preferably from 6 to 10 (for example: caprylic acid, lauric acid and azelaic acid); and diols of formula HO-CH2(CH2)mCH2-OH, where m is as defined above (for example: 1 ,12-dodecanediol). The term "substantially free" in this context means that the further linker molecules described above are not intentionally added to the composition, although incidental trace quantities may occur, such as no more than 0.1 %, preferably no more than 0.01 %, and more preferably from 0 to 0.001 % by weight based on the total weight of the composition. The composition of the invention includes at least one inorganic electrolyte. The inorganic electrolyte is used to assist in the solubilisation of the oily liquid conditioning agent and to provide viscosity to the composition. The viscosity of the composition suitably ranges from 3,000 to 10,000 mPa.s, preferably from 4,000 to 9,000 mPa.s when measured using a Brookfield V2 viscometer (spindle RTV5, 1 minute, 20rpm) at 30°C. Suitable inorganic electrolytes include metal chlorides (such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, zinc chloride, ferric chloride and aluminium chloride) and metal sulphates (such as sodium sulphate and magnesium sulphate). Examples of preferred inorganic electrolytes for use in the invention include sodium chloride, potassium chloride, magnesium sulphate and mixtures thereof.

Mixtures of any of the above described materials may also be suitable. The level of inorganic electrolyte in compositions of the invention depends on the particular oily liquid conditioning agent (s) used, but generally ranges from about 1 to about 25%, preferably from about 1.5 to about 20% (by total weight inorganic electrolyte based on the total weight of the composition). The composition of the invention may suitably include other hair and/or skin conditioning ingredients in addition to the oily liquid conditioning agent (as defined above). Examples of such other conditioning ingredients include emulsified, non-volatile silicones.

Emulsified, non-volatile silicones are typically present in the composition as droplets having a mean droplet diameter (D3,2) of 4 micrometres or less. Preferably the mean droplet diameter (D3,2) is 1 micrometre or less, more preferably 0.5 micrometre or less, and most preferably 0.25 micrometre or less.

A suitable method for measuring the mean droplet diameter (D3,2) is by laser light scattering using an instrument such as a Malvern Mastersizer.

For the purposes of the present invention, the term "non-volatile silicone" means a silicone that has a vapour pressure of less than 1000 Pa at 25°C. Suitable emulsified, non-volatile silicones for use in the invention include polydiorganosiloxanes, in particular polydimethylsiloxanes (dimethicones), polydimethyl siloxanes having hydroxyl end groups (dimethiconols), and amino-functional

polydimethylsiloxanes (amodimethicones).

Suitable emulsified, non-volatile silicones preferably have a molecular weight of greater than 100,000 and more preferably a molecular weight of greater than 250,000. All molecular weights as used herein are weight average molecular weights, unless otherwise specified.

Suitable emulsified, non-volatile silicones preferably have a kinematic viscosity of greater than 500,000 cS (mm².s^"1) and more preferably a kinematic viscosity of greater than 1 ,000,000 cS (mm².s^"1). Silicone kinematic viscosities in the context of this invention are measured at 25°C and can be measured by means of a glass capillary viscometer as set out further in Dow Corning Corporate Test Method CTM004 July 20, 1970.

Suitable emulsified, non-volatile silicones for use in compositions of the invention are available as pre-formed silicone emulsions from suppliers such as Dow Corning and GE Silicones. The use of such pre-formed silicone emulsions is preferred for ease of processing and control of silicone particle size. Such pre-formed silicone emulsions will typically additionally comprise a suitable emulsifier, and may be prepared by a chemical emulsification process such as emulsion polymerisation, or by mechanical emulsification using a high shear mixer. Pre-formed silicone emulsions having a mean droplet diameter (D3,2) of less than 0.15 micrometers are generally termed microemulsions.

Examples of suitable pre-formed silicone emulsions include emulsions DC2-1766, DC2- 1784, DC-1785, DC-1786, DC-1788, DC-1310, DC-7123 and microemulsions DC2-1865 and DC2-1870, all available from Dow Corning. These are all emulsions/microemulsions of dimethiconol. Also suitable are amodimethicone emulsions such as DC939 (from Dow Corning) and SME253 (from GE Silicones). Mixtures of any of the above described silicone emulsions may also be used.

The amount of emulsified, non-volatile silicone in compositions of the invention may suitably range from 0.05 to 10%, preferably from 0.2 to 8% (by total weight silicone based on the total weight of the composition).

The composition of the invention preferably includes one or more cationic polymers. Such polymers may enhance the delivery of conditioning agents and thereby improve the conditioning benefits obtained.

Cationic polymers typically contain cationic nitrogen-containing groups such as quaternary ammonium or protonated amino groups. The cationic protonated amines can be primary, secondary, or tertiary amines (preferably secondary or tertiary). The average molecular weight of the cationic polymer is preferably from 5,000 to 10 million. The cationic polymer preferably has a cationic charge density of from 0.2 meq/gm to 7 meq/gm.

The term "cationic charge density" in the context of this invention refers to the ratio of the number of positive charges on a monomeric unit of which a polymer is comprised to the molecular weight of the monomeric unit. The charge density multiplied by the polymer molecular weight determines the number of positively charged sites on a given polymer chain.

The cationic nitrogen-containing moiety of the cationic polymer is generally present as a substituent on all, or more typically on some, of the repeat units thereof. The cationic polymer may be a homo-polymer or co-polymer of quaternary ammonium or cationic amine-substituted repeat units, optionally in combination with non-cationic repeat units. Particularly suitable cationic polymers for use in the invention include cationic

polysaccharide polymers, such as cationic cellulose derivatives, cationic starch derivatives, and cationic guar gum derivatives.

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, JAGUAR® C15 and JAGUAR ® C17.

Mixtures of any of the above described cationic polymers may also be used.

When included, the total level of cationic polymer in the composition is preferably from 0.05% to 2% and more preferably from 0.1 to 0.5% by weight based on the total weight of the composition.

The composition of the invention preferably includes one or more amphoteric surfactants. Suitable amphoteric surfactants are betaines, such as those having the general formula R(CH3)2N⁺CH2COO^", where R is an alkyl or alkylamidoalkyl group, the alkyl group preferably having 10 to 16 carbon atoms. Particularly suitable betaines are oleyl betaine, caprylamidopropyl betaine, lauramidopropyl betaine, isostearylamidopropyl betaine, and cocoamidopropyl betaine. When included, the total level of amphoteric surfactant is generally from 0.1 % to 20%, preferably from 1 % to 10%, more preferably from 1 % to 5% by weight based on the total weight of the composition.

The composition of the invention preferably includes one or more suspending agents. Suitable suspending agents include 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. Mixtures of any of the above suspending agents may be used. Preferred is a mixture of cross-linked polymer of acrylic acid and crystalline long chain acyl derivative.

When included, the total level of suspending agent is generally 0.1 to 10%, preferably from 0.5 to 6%, more preferably from 0.9 to 4% by weight based on the total weight of the composition. A composition of the invention may contain further optional ingredients to enhance performance and/or consumer acceptability. Examples of such ingredients include fragrance, dyes and pigments and pH adjusting agents. Each of these ingredients will be present in an amount effective to accomplish its purpose. Generally these optional ingredients are included individually at a level of up to 5% by weight based on the total weight of the composition.

The composition of the invention is preferably substantially free of preservatives selected from methylparaben, ethylparaben, propylparaben, butylparaben, formaldehyde,

Quaternium-15 (c/s-1-(3 chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride), imidazolidinyl urea, diazolidinyl urea, 2-bromo-2-nitropropane-1 ,3-diol (bronopol), 1 ,3-dimethylol-5,5-dimethyl hydantoin (DMDM hydantoin), methylchloroisothiazolinone (MCI), methylisothiazolinone (Ml), benzothiazolinone, phenoxyethanol,

methyldibromoglutaronitnle, potassium sorbate, 3-iodo-2-propynyl-butylcarbamate (IPBC) and mixtures thereof.

The term "substantially free" in this context means that the preservatives described above are not intentionally added to the composition, although incidental trace quantities may occur, such as no more than 0.1 %, preferably no more than 0.01 %, and more preferably from 0 to 0.001 % by weight based on the total weight of the composition.

The pH of the composition of the invention is below 5.1 , and preferably ranges from 3.0 to 5.1 , more preferably from 3.5 to 4.2 and most preferably from 3.9 to 4.1.

The composition of the invention is primarily intended for topical application to the body, preferably 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 prior to drying the hair. The invention will be further illustrated by the following, non-limiting Examples, in which all percentages quoted are by weight based on total weight unless otherwise stated.

EXAMPLES

Effect of benzoic acid on creating oil microemulsion phase

A series of hair cleansing shampoo formulations were prepared, having ingredients as shown in Table 1 below.

Table 1

Ingredient Example A Example 1 Example B Example 2

(%w/w)

Sodium laureth sulphate 1 1.63 1 1.63 11.63 11.63

Cocoamidopropyl betaine 1.63 1.63 1.63 1.63

Perfume 0.75 0.75 0.75 0.75

Lytol®(mineral oil, ex Sonneborn) 0.9 0.9 1.8 1.8

Disodium EDTA 0.05 0.05 0.05 0.05

Sodium benzoate 0 0.5 0 0.5

NaCI 1.5 1.5 3 3

Water To 100% To 100% To 100% To 100%

PH 4 4 4 4

Phase 2-phase 1 -phase 2-phase 1 -phase observation (micro (micro emulsion) emulsion)

Type of structure Worm-like Worm- 1 ike micelles micelles Table 1 (...cont'd)

Ingredient Example C Example 3

(%w/w)

Sodium laureth sulphate 11.63 11.63

Cocoamidopropyl betaine 1.63 1.63

Perfume 0.75 0.75

Lytol®(mineral oil, ex Sonneborn) 2.7 2.7

Disodium EDTA 0.05 0.05

Sodium benzoate 0 0.5

NaCI 5 5

Water To 100% To 100%

PH 4 4

Phase 2-phase 1 -phase observation (micro emulsion)

Type of structure Worm- 1 ike micelles

Table 1 (...cont'd)

Ingredient Example D Example 4 Example E Example 5

(%w/w)

Sodium laureth sulphate 1 1.63 11.63 11.63 1 1.63

Cocoamidopropyl betaine 1.63 1.63 1.63 1.63

Perfume 0.75 0.75 0.75 0.75

Puresyn™ 6 0.5 0.5

(hydrogenated polydecene, ex ExxonMobil)

Puresyn™ 3E20 (trimethylolpropane 0.45 0.45 tricaprylate/tricaprate, ex ExxonMobil)

Citric acid 0.5 0.5 0.5 0.5

Disodium EDTA 0.05 0.05 0.05 0.05

Sodium benzoate 0 0.5 0 0.5

NaCI 4 4 2.5 2.5

Water To 100% To 100% To 100% To 100%

PH 4 4 4 4

Phase observation 2-phase 1 -phase 2-phase 1 -phase

(micro (micro emulsion) emulsion)

Type of structure Worm- 1 ike Worm-like micelles micelles Table 1 (...cont'd)

*Benzoic acid is the dominant form for sodium benzoate at pH4 The above formulations were made by mixing the ingredients and putting the mixture on roller mixer overnight to allow a thorough mix. The sample was then kept in a 50°C oven for 2 hours for the purpose of de-aeration. After temperature returned to ambient, and the formulation had reached equilibrium, the sample was checked visually for any phase separation or micellisation of oil.

The results show that Examples 1 to 7 (according to the invention) are in microemulsion phase which is a stable formula. By contrast, Examples A to G (not according to the invention) exhibit phase separation with an oil layer sitting on top of the aqueous phase.

Benefit from benzoic acid-oil formulations

Hair cleansing shampoo formulations were prepared, having ingredients as shown in Table 2_below. Examples 8 and 9 represent formulations according to the invention. "Control" represents a control formulation (not according to the invention).

Table 2

*Benzoic acid is the dominant form for sodium benzoate at pH4

The above formulations were made by pre-dispersing the carbomer with citric acid at pH 2 to 3 to form a slurry at 3%. Then this carbomer slurry was added slowly to 25% sodium laureth sulphate (1 EO) solution in the main beaker under overhead mechanical shearing. In a separate beaker, the JAGUAR® C14/C17 was mixed with fragrance and the premix dosed into the main beaker. Mica was pre-dispersed in 10 portions of water (wt%) and the dispersion was added to the main beaker. The remaining ingredients were added in sequentially. The pH of the shampoo was adjusted to around 4 by citric acid. All ingredients in the main beaker were allowed to mix until a homogeneous shampoo was obtained.

Shampoo performance was evaluated by measuring the alignment of hair treated with the respective formulations. 0.5g test formulation was applied to 5g/10" dark brown European (DBE) wet hair. The formulation was massaged on hair for 30 seconds followed by rinsing with warm water for 30 seconds. The treatment was repeated once. Five replicas were produced for each formulation.

The alignment of hair was measured by Rumba instrument. Higher rumba coefficient score means better alignment. The results are shown in Table 3 below.

Table 3

The results show that Examples 8 and 9 (according to the invention) provide significantly more hair alignment than the control.

Silicone deposition was measured by XRF. 0.25g test formulation was applied to 2.5g/6" dark brown European (DBE) wet hair. The formulation was massaged on hair for 30 seconds followed by rinsing with warm water for 30 seconds. The treatment was repeated once. Five replicas were produced for each formulation. The results are shown in Table 4 below.

Table 4

It can be seen that Examples 8 and 9 according to the invention both deliver significantly more silicone than their respective controls.

Claims

A personal cleansing composition with a pH below 5.1 , the composition having an aqueous continuous phase including cleansing surfactant; and an oil phase including at least one oily liquid conditioning agent for skin and/or hair; in which the oily liquid conditioning agent is solubilised in wormlike micelles in the aqueous continuous phase via the incorporation of at least one inorganic electrolyte and at least one linker molecule which is selected from organic carboxylic acids of general formula (I):

R(COOH) (I) in which R is an aromatic hydrocarbyl group having from 6 to 10 carbon atoms; and in which the level of the oily liquid conditioning agent in the composition ranges from 0.45 to 3% by weight based on the total weight of the composition.

A composition according to claim 1 , in which the oily liquid conditioning agent is selected from oily liquid hydrocarbons, oily liquid esters, silicone oils and mixtures thereof.

A composition according to claim 2, in which the oily liquid conditioning agent is

light mineral oil having a kinematic viscosity of 3.9 to 5.0 cS (mm².s^"1) at 40°C and a specific gravity of 0.810 to 0.830 at 25°C.

4. A composition according to any one of claims 1 to 3, in which the level of solubilised hydrocarbon oil ranges from 0.5 to 1.5% by weight based on the total weight of the composition.

5. A composition according to any preceding claim, in which R in general formula (I) is an aromatic hydrocarbyl ring having 6 carbon atoms.

6. A composition according to claim 5, in which the linker molecule is benzoic

acid.

7. A composition according to any preceding claim, which also includes emulsified droplets of silicone having a mean droplet diameter (D3,2) of 0.25 micrometre or less, in an amount ranging from 0.2 to 8% by total weight silicone based on the total weight of the composition.

8. A composition according to any preceding claim, which also includes one or more cationic polymers.

9. A composition according to any preceding claim, in which the pH ranges from 3.0 to 5.1.

10. A method of cleansing and conditioning hair, comprising the following

sequential steps:

(i) topically applying a composition according to any one of claims 1 to 9 to the hair;

(ii) massaging the composition into the hair and scalp;

(iii) rinsing the composition off the hair and scalp with water, and

(iv) drying the hair.