WO2008007059A1

WO2008007059A1 - Emulsification systems, emulsions and wet wipes containing such emulsions

Info

Publication number: WO2008007059A1
Application number: PCT/GB2007/002533
Authority: WO
Inventors: Graham Timothy Pennick; Trevor Graham Blease; Franciscus Johannes Groenhof
Original assignee: Croda International Plc; Unichema Chemie Bv
Priority date: 2006-07-10
Filing date: 2007-07-05
Publication date: 2008-01-17
Also published as: GB0613636D0

Abstract

An oil-in-water emulsion is described which has an oil emulsifier, a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1, and at least an effective amount of at least one electrolyte. A wipe having a wipe substrate impregnated with the oil-in-water emulsion is also disclosed.

Description

Emulsification Systems, Emulsions and Wet Wipes Containing such Emulsions

The invention relates to emulsification systems, emulsions, wet wipes containing such emulsions.

Oil-in-water emulsions are widely used in the personal care and cosmetic industry to deliver ingredients to skin and hair, either by direct application thereto of milks or lotions or through the medium of wet wipes and other similar applicators.

Personal care emulsion products such as creams and milks desirably have a number of properties in combination: stability in manufacture, formulation, storage and use; a viscosity appropriate to the end use; and preferably a desirable body and good skin feel. Body and skin feel are usually assessed subjectively, and although good body and/or skin feel are commonly associated with a non-Newtonian, shear thinning viscosity profile, a shear thinning profile does not guarantee a good body or skin feel. Typical conventional personal care emulsion products use emulsifiers (including emulsion stabilisers) in amounts of about 3% to about 5% by weight of the emulsion. Recently, thickeners have been proposed as emulsion stabilisers and the mechanism of stabilisation when these are used appears to be that the thickener increases the low shear viscosity of the emulsion sufficiently to provide a barrier to emulsion droplet coalescence, probably by limiting the movement of the droplets.

A particularly effective emulsification system is described in EP 1137396 B1 , which is incorporated herein in its entirety by reference, wherein certain combinations of high molecular weight polysaccharides provide good emulsion stabilisation at levels that do not give high, or even significantly increased, low shear viscosity and that using such combinations, the amount of emulsifier, usually a relatively low molecular weight, often non-ionic, surfactant can be much less than is used conventionally in emulsions, particularly emulsions for personal care products such as cosmetic skin creams and milks.

Thus, EP 1137396 B1 discloses personal care or cosmetic oil-in-water emulsions in which an emuisifier stabiliser system comprises an emulsifier for the oil and a polysaccharide combination of a Xanthan polysaccharide and a polyglucomannan polysaccharide, preferably in a weight ratio of 1:1. The combined amount of emulsifier and polysaccharide stabiliser in such emulsions can be much lower than the typical 3% to 5% used in conventional personal care emulsion systems. In particular, in many emulsions disclosed in EP 1137396 B1, the amount of emulsifier can be less than about 1.5%, particularly up to about 1%, and the amount of polysaccharide stabiliser can be less than about 0.5%, and sometimes as little as about 0.02%, desirably with the combined amount being less than about 1.5%, particularly up to about 1%. The minimum amount of emulsifier is typically about 0.02% more usually 0.025% by weight of the emulsion.

The preparation of emulsions as disclosed in EP 1137396 B1 requires the emulsion/polysaccharide stabiliser mixture to be heated above about 60⁰C in the aqueous phase and/or subjected to high intensity mixing to ensure the polysaccharide stabiliser functions effectively. Although phase inversion emulsification, in which the emulsifier and polysaccharide stabiliser is initially mixed into the oil phase, is mentioned as an option in EP 1137396 B1, it is still necessary to have the heating and/or high intensity mixing step in the emulsification process. The normal practise is to mix the emulsifier and polysaccharide stabiliser into the aqueous phase, for example as disclosed in US 2005/0009431 A1 wherein, in the examples, Arlatone V 175™ emulsifier/ polysaccharide stabiliser material within the scope of EP 1137396 B1 is mixed into the aqueous phase using a triblender. In a similar disclosure to EP 1137396 B1, WO 01/96461 A1 discloses initially making a fluid gel using Xanthan and one or more non-gelling polysaccharides such as galactomannans and gluccomannans by heating an aqueous mixture of Xanthan and the non-gelling polysaccharide to temperatures greater than 50⁰C and allowing it to cool whilst subjecting it to shear. The fluid gels are then used in personal care and cosmetic formulations including those using oil-in-water emulsions.

One use of oil-in-water emulsions is in the preparation of wet wipes for skin cleansing. The aforementioned US 2005/0009431 A1, together with US 2005/0008680 A1 and US 2005/0008681 A1 published on the same day, which are incorporated herein in their entirety by reference, provide a useful background to the uses to which wet wipes are put as well as the materials that they are made of.

US 2005/0009431 A1 describes a method of making a wet wipe in which a concentrated emulsion composition consisting of emollient, surfactant and not more than about 30% by weight of water, is made initially and the concentrate is then diluted down with further water to become an oil-in-water emulsion before being applied to a wipe substrate.

As will be appreciated, wet wipes are a high volume consumer product used for a wide variety of cleansing purposes. Consequently, the high energy requirements for the manufacture of suitable oil-in-water emulsions for use in making the wipes requires a high capital investment as well as high manufacturing costs - as is recognised in US 2005/0009431 A1. Even the process described in US 2005/0009431 A1, whilst avoiding some of the costs inherent in the earlier manufacturing methods, still involves a two-stage process, additional emulsifier costs (in making the initial concentrate) and additional equipment and running costs (for the inclusion of products of the type described in EP 1137396 B1). As described in PCT Patent Application GB 2007/000143, it was found that the aforementioned disadvantages can be significantly reduced or overcome by using the method described therein to make oil-in-water emulsions using an oil emulsifier and a polysaccharide emulsion stabiliser without the need to heat the emulsion or subject it to high shear. In accordance with the method described in GB 2007/000143, an oil-in-water emulsion is made by dispersing an oil emulsifier and a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide, in an oil, combining the oil-based dispersion so formed with water, preferably at low temperature and under low shear conditions, to form an oil-in-water emulsion.

In that method, a polysaccharide emulsion stabiliser and optionally oil emulsifier may be effectively dispersed in oils that are relatively polar. Alternatively, when the oil(s) are relatively non-polar, the polysaccharide emulsion stabiliser and optionally oil emulsifier may be effectively dispersed in a relatively polar non-aqueous liquid medium, which medium being mixed with the oil prior to the step of combining the oil- based dispersion with the water to form the emulsion. If required, the dispersion of the polysaccharide emulsion stabiliser and optionally oil emulsifier in a relatively polar non-aqueous liquid medium may also be used even when the oil is relatively polar. The oil emulsifier may be dispersed separately in the non-polar oil, polar oil and/or non-aqueous liquid medium as required, but is preferably dispersed together with and in the same oil/medium as the polysaccharide emulsion stabiliser.

However, despite the utility of such emulsifier compositions, the presence of electrolytes tends to destabilise the emulsions. In applications such as wet wipes, electrolytes such as sodium benzoate, frequently in combination with ethylene diamine tetra-acetic acid (EDTA), are used as preservatives. As is demonstrated in the comparative examples described herein below, even using higher concentrations of polysaccharide emulsion stabiliser and low concentrations of ionic materials as suggested in EP 1137396 B1, good emulsions cannot be obtained in the presence of such electrolytes as sodium benzoate. The Applicant has now surprisingly found that a novel selection of components for the emulsion enables stable emulsions containing electrolytes to be made, such emulsions having particular utility in wet wipes.

Thus, in accordance with the present invention, an oil-in-water emulsion comprises 1% to 10% by weight of the emulsion of a discontinuous oil phase, at least an effective amount of oil emulsifier, and 0.05% to 0.25% by weight of the emulsion of a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1, and at least an effective amount of at least one electrolyte. Preferably, the emulsion comprises at least 0.1% by weight of the emulsion of the polysaccharide emulsion stabiliser. Preferably, the emulsion comprises not more than 0.2% by weight of the emulsion of the polysaccharide emulsion stabiliser.

Preferably, the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is greater than 2:1 and is more preferably at least 4:1 and more especially is at least 5:1. Preferably, the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is not more than 100:1 and is more preferably not more than 50:1 and more especially is not more than 20:1. In particularly, preferred embodiments, the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is not more than 15:1 and is especially not more than 12:1.

Also, according to the present invention, a wipe comprises a wipe substrate impregnated with an oil-in-water emulsion, said emulsion comprising 1% to 10% by weight of the emulsion of a discontinuous oil phase, at least an effective amount of oil emulsifier, and 0.05% to 0.25% by weight of the emulsion of a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1, and at least an effective amount of at least one electrolyte.

The emulsions of the present invention may be made using the method described in the aforementioned GB 2007/000143. As described above, the method involves dispersing the polysaccharide emulsion stabiliser and optionally oil emulsifier in oils that are relatively polar; or, alternatively, when the oil(s) are relatively non-polar, in a relatively polar non-aqueous liquid medium.

A measure of the polarity of the oil or the non-aqueous medium may be obtained using solubility parameters. A widely used solubility parameter is the Hansen and Beerbower solubility parameter as described in A F M Barton, CRC Handbook of Solubility parameters and other cohesion parameters, CRC press, 1983 p. 85-87 and A F M Barton in Chemical Reviews, 1975, VoI 75 No.6 p.731-753.

In a more specific embodiment described in GB 2007/000143, a method of making an oil-in-water emulsion comprises the steps of:

(a) dispersing a polysaccharide emulsion stabiliser and optionally an oil emulsifier, wherein said polysaccharide emulsion stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide, either in: (i) an emollient oil with a Hansen and Beerbower solubility parameter of at least 19 but less than 45; or

(ii) a non-aqueous liquid medium with a Hansen and Beerbower solubility parameter of at least 19 but less than 45 and combining the dispersion in said medium with an oil that has a Hansen and Beerbower solubility parameter of at least 19 but less than 45; or

(iii) a non-aqueous liquid medium with a Hansen and Beerbower solubility parameter of at least 19 but less than 45 and combining the dispersion in said medium with an oil that has a Hansen and Beerbower solubility parameter of less than 19;

(b) combining water with the oil-based dispersion formed in step (a), preferably at low temperature and under low shear conditions, to form an oil-in-water-emulsion, and

(c) continuing to mix the emulsion formed in step (b), preferably under low shear conditions, until homogenous.

It will be understood that, for certain classes of emollient oils, for example silicone oils, it is not possible to assign a Hansen and Beerbower solubility parameter. In such instances, in accordance with the method of the present invention, the emollient oil is treated as though it has a Hansen and Beerbower solubility parameter of less than 19 and a dispersion is made in accordance with step (a)(iii) in the preceding paragraph. For the avoidance of doubt, emollient oils that do not have Hansen and Beerbower solubility parameter assigned or assignable to them are treated for the purposes of this specification, including the claims, as having a Hansen and Beerbower solubility parameter of less than 19 and, thus, are intended to be within the relevant wording used in the specification, including the claims.

By the term "low temperature" as used in the methods of described in GB 2007/000143 is meant a temperature of not more than 50⁰C, preferably not more than 40⁰C and especially not more than 30⁰C. Additionally, the term "low temperature" as used in the methods described in GB 2007/000143 means a temperature of greater than 0°C, preferably at least 10⁰C, and especially at least 15°C. Preferred temperatures for use in the methods described in GB 2007/000143 are in the range 15°C to 30⁰C, more especially in the range 2O⁰C to 25⁰C. By the term "low shear" as used in the methods described in GB 2007/000143 is meant a shear rate of not more than 5000 s^"\ Additionally, the term "low shear" as used in such methods means a shear rate of greater than 10 s^"1, preferably at least 50 s-¹.

No special mixing device is required to combine the solid additives and emollient oil as the emulsifier and polysaccharide emulsion stabiliser are readily dispersed (either in the emollient oil or in the non-aqueous medium and then subsequently the emollient oil) even when using conventional "low shear" mixing devices such as vessels with internal rotors (eg anchor, flat blade, angled blade, propeller agitators with two or more blades) operating at rotational speeds of less than 1000 rpm, preferably less than 500 rpm, with a specific power input of less than 1000 W/m3 of total vessel volume, or vessels operating with jet mixers or external piping mixing devices operating on a pump-round loop or in a continuous flow configuration. The same types of simple mixing system are sufficient to carry out all the process steps from initial dispersion preparation to final emulsion. The initial volumes of emulsifier/stabiliser, non-aqueous liquid medium (when present) and emollient oil are relatively low compared to the final emulsion volume. Therefore, it is necessary to ensure that the mixing device is in contact with the liquids for the initial production steps. This can be achieved by the use of several agitator blades situated at different heights up the vessel, such that the lowest blade provides the necessary agitation for the initial dispersion; by mounting a single impeller sufficiently close to the vessel base such that it is in contact with the initial volume; by using several vessels of increasing size in sequence for the production steps; by employing one or more pump-round loops of different volumes external to the vessel with jet mixing or other in-line mixing devices (eg static mixers, or powered rotating mixing devices); by using similar continuous in-line mixing techniques in a piping system or any combination of these together or in isolation. As will be appreciated, such systems may be operated either on a batch basis or a continuous basis depending on the configuration of the equipment used.

Suitable non-aqueous liquid media may be selected from relatively polar emollient oils, preferably with a Hansen and Beerbower solubility parameter of at least 19 but less than 45, alcohols, glycols and glycerine and mixtures thereof. Examples of suitable emollient oils are stearyl alcohol 15-propoxylates (solubility parameter 20.8), glyceryl isostearate (solubility parameter 21.3), propylene glycol isostearate (solubility parameter 19.54) and a mixture of triethylhexanoin and isopropyl isostearate (solubility parameter 19.04). Examples of other non-aqueous liquid media are glycerine (solubility parameter 38) and propylene glycol (solubility parameter 31). It will be understood that any such non-aqueous media have to be suitable for use in personal care applications. Preferably, the non-aqueous media are those registered as solvents by the Cosmetics Toiletries and Fragrance Association. A particularly preferred non-aqueous liquid medium is propylene glycol.

Whilst small amounts of water, ie not greater than 1% by weight, may be present in the oil phase, preferably the oil phase is essentially water free; although it will be appreciated any residual water (moisture) content in the components thereof will be present. More particularly, the amount of emulsifier/polysaccharide stabiliser combination added to the non-aqueous medium is in the range 1 % to 20% by weight based on the weight of the non-aqueous medium and emollient oil, more preferably, in the range 5% to 15% by weight based on the weight emollient oil or non-aqueous medium.

The amount of non-aqueous medium added to the emollient oil is such that the amount of non-aqueous medium in the final emulsion is preferably not more than about 5%, more preferably not more than about 3%, and especially not more than about 2%, by weight of the final emulsion. Preferably, the amount of non-aqueous medium added to the emollient oil is such that the amount of non-aqueous medium in the final emulsion is preferably not less than about 0.25%, more preferably not less than about 0.5%, by weight of the final emulsion.

More particularly, the amount of non-aqueous medium added to the emollient oil is in the range 10% to 80% by weight based on the weight of the emollient oil, more preferably, in the range 20% to 50% by weight based on the weight of the emollient oil. The invention includes an emollient oil composition comprising emollient oil in which is dispersed at least an effective amount of oil emulsifier based on the composition of a final oil-in-water emulsion made from the emollient oil composition and 0.05% to 0.25% by weight of a final oil-in-water emulsion made from the emollient oil composition of a polysaccharide emulsion stabiliser wherein said polysaccharide emulsion stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1.

The invention also includes an emollient oil composition comprising emollient oil and a non-aqueous liquid medium with a Hansen and Beerbower solubility parameter of at least 19 but less than 45 in which is dispersed an effective amount of an oil emulsifier and a polysaccharide emulsion stabiliser wherein said polysaccharide emulsion stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1 :1.

In an alternative embodiment of the invention, the polysaccharide emulsion stabiliser may be added to the aqueous phase, preferably by premixing in a polyol prior to adding to water. Suitable polyols include sugar alcohols such as sorbitol, mannitol; (poly)glycols such as (poly)ethylene glycol, (poly)propylene glycol, pentaerythritol, dipentaerythritol, neopentyl glycol; and other C₃-C₆ polyols containing from 3 to 6 hydroxyl groups such as trimethylolpropane, trimethylolethane, and glycerine. Glycerine is a preferred polyol. The resultant mixture can be stirred, suitably with heating, preferably at a temperature of greater than 50°C, more preferably greater than 60⁰C, and especially in the range 75°C to 90⁰C. The ratio by weight of the polysaccharide emulsion stabiliser to polyol, preferably glycerine, is preferably in the range from 1:2 to 1:50, more preferably 1:5 to 1:20, and especially 1:8 to 1:12. An oil emulsifier may then be added, preferably after the polysaccharide emulsion stabiliser is completely dispersed. The aqueous phase can then be combined with the oil phase to form an oil-in-water emulsion by direct or indirect emulsification route.

Concentrated aqueous phases may be made which can be used as pre- manufactured concentrates for combination with additional water, oil and other components if desired to make product emulsions. Such a concentrate is a further embodiment of the present invention.

Thus, according to the present invention, an aqueous composition comprises (i) water, (ii) at least 0.5% by weight of polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1; (iii) at least 5% by weight of polyol; and optionally (iv) at least 1 % by weight of emulsifier.

Such aqueous composition concentrates preferably comprise, consist essentially of, or consist of, (i) at least 70%, more preferably at least 78%, and especially in the range from 82% to 88% by weight of water, (ii) at least 0.5%, more preferably in the range from 0.9% to 2%, and especially 1.2% to 1.5% by weight of polysaccharide emulsion stabiliser; (iii) at least 5%, more preferably in the range from 8% to 20%, and especially 10% to 15% by weight of polyol, and optionally (iv) at least 1%, more preferably in the range from 1.8% to 4%, and especially 2.4% to 3% by weight of oil emulsifier.

Also, if desired, concentrated oil-in-water emulsions may be made. Such concentrates may contain at least 45% by weight of water, more preferably at least 50% by weight of water. Conversely, the concentrates may contain not more than 80% by weight of water, more preferably not more than 75% by weight of water. Such concentrated emulsions may be used as pre-manufactured concentrates for combination with additional water, and other components if desired to make product emulsions.

Preferably, the amount of emulsifier added to the emollient oil or non-aqueous or aqueous medium is such that the amount of emulsifier in the final emulsion is not more than about 1.5%, particularly not more than about 1%, by weight of the final emulsion. Preferably, the combined amount of emulsifier and polysaccharide stabiliser added to the emollient oil or non-aqueous or aqueous medium is such that the amount of emulsifier and polysaccharide stabiliser in the final emulsion is not more than about 1.5%, particularly not more than about 1%, by weight thereof and especially not more than 0.5% by weight thereof. The minimum amount of emulsifier in the final emulsion is typically about 0.05% by weight of the emulsion.

The amount of oil used to form the final emulsion will depend upon the use to which the emulsion will be put. For example, personal care emulsions can be divided by viscosity into milks and lotions, which typically have a low shear viscosity of up to about 10000 mPa.s, and creams which typically have a low shear viscosity of more than about 20000 mPa.s. Typically, milks and lotions have a low shear viscosity of from about 100 to about 10000 mPa.s, more usually from about 500 to about 5000 mPa.s, and typically creams have a low shear viscosity of at least about 30000 mPa.s, particularly from about 30000 to about 80000 mPa.s, although even higher viscosities e. g. up to about 106 mPa.s, may also be used. In this context low shear viscosity refers to viscosity measured at shear rates of about 0.1 to 10 s^'1 as is typically used in Brookfield viscometers. Because for good skin feel, personal care and cosmetic emulsions are usually shear thinning, the measured low shear viscosity is only a general guide to whether the product is a milk (or lotion) or cream. Products of the present invention includes both milk (and lotion) and cream emulsions and specifically include personal care or cosmetic oil-in-water emulsion milks or lotions having a low shear viscosities of up to about 10000 mPa.s, which includes as an emulsifier stabiliser system an emulsifier for the oil and a polysaccharide stabiliser. Such products further includes personal care or cosmetic oil-in-water cream emulsions having a low shear viscosity of more than about 20000 mPa.s, which includes as an emulsifier stabiliser system an emulsifier for the oil and a polysaccharide stabiliser, the emulsion further including thickener components.

More particularly, when the emulsions of the present invention are intended for application to wipe substrates, the oil-in-water emulsions have low shear viscosities of not more than about 1000 mPa.s, more preferably not more than about 800 mPa.s, and more especially not more than about 500 mPa.s. Such oil-in-water emulsions have low shear viscosities of not less than about 50 mPa.s, more preferably not less than aboutlOO mPa.s, more especially not less than about 200 mPa.s. Generally the concentration of electrolytes, or ionic materials, will be not greater than about 0.05 molar, desirably not more than about 0.02 molar and particularly not more than about 0.01 molar.

The oil emulsifier used in the invention is desirably one or more non-ionic emulsifier(s). Suitable emulsifiers include conventional non-ionic oil-in-water emulsifier surfactants such as alkoxylate emulsifiers and surfactants that can be derived from natural materials such as fatty acid esters, ethers, hemi-acetals or acetals of polyhydroxylic compounds. The specific nature of the emulsifier surfactant used in any particular instance depends on the type of emulsion being made, particularly whether fatty amphiphilic thickeners are being used, the degree of stability required, the nature of the oil being emulsified and the total desired level of emulsifier/stabiliser system.

The term alkoxylate emulsifier is used to refer to surfactants in which a hydrophobe, usually a hydrocarbyl group, is connected through the residue of a linking group having a reactive hydrogen atom to an oligomeric or polymeric chain of alkylene oxide residues. The hydrocarbyl group Is typically a chain, commonly an alkyl chain, containing from 8 to 24, particularly 12 to 22, and usually 14 to 20 carbon atoms. The linking group can be an oxygen atom (hydroxyl group residue); a carboxyl group (fatty acid or ester residue); an amino group (amine group residue); or a carboxyamido (carboxylic amide residue). The alkylene oxide residues are typically residues of ethylene oxide (C₂H₄O) or propylene oxide (C₃H₆O) or combinations of ethylene and propylene oxide residues. When combinations are used the proportion of ethylene oxide residues will usually be at least about 50 mole% and more usually at least 75 mo!e%, the remainder being propylene oxide residues. Particularly and desirably, substantially all the residues are ethylene oxide residues. The number of alkylene residues in the emulsifier molecule is desirably from 2 to about 200.

It can be useful to use a combination of different types of emulsifier and in particular to combine hydrophilic emulsifiers ie having a high Hydrophile Lipophile Balance (HLB), eg more than about 12, and hydrophobic emulsifiers, ie having a low HLB, eg less than about 8, in making the emulsions of the invention. Relatively hydrophilic emulsifiers include alkoxylate emulsifiers with an average of from about 10 to about 100 alkylene oxide, particularly ethylene oxide residues; and non-alkoxylate emulsifiers including sugar mono-esters and polyglycerol mono-esters, hydrocarbyl, especially alkyl, polysaccharides; fatty acid glycerol esters where the fatty acid has 8 to 12 carbon atoms such as glycerol mono-laurate and fatty acid N-sugar amides such as glucamides. Relatively hydrophilic emulsifiers include alkoxylate emulsifiers with an average of from 2 to about 10 alkylene oxide, particularly ethylene oxide residues; glycerol esters where the fatty acid has 14 to 24 carbon atoms such as glycerol mono-stearate.-oleate, or-laurate; and anhydrosaccharide fatty esters such as sorbitan mono-stearate,-oleate, or-laurate. The amount of emulsifier used is typically from about 0.02% to about 1.5%, more usually from about 0.025% to about 1.2%, particularly from about 0.025% to about 1 %, by weight of the emulsion.

Where hydrophilic alkoxylate emulsifiers, especially those with HLB greater than about 12, are used, it is possible to obtain satisfactory emulsions with very low levels of emulsifier for example from as little as about 0.04% to about 0.1 % by weight of the emulsion, and this forms a particular feature of the invention. Higher amounts of such emulsifiers can be used eg in the overall range about 0.04% to about 0.8%, particularly about 0.1% to about 0.6%, by weight. Where less hydrophilic alkoxylate emulsifiers are used as the primary emulsifier, the concentration used will typically be higher eg in the range from about 0.1% to about 1.5%, more usually from about 0.2% to about 1.2%, particularly from about 0.5% to about 1%, by weight of the emulsion. Similarly where non-alkoxylate emulsifiers such as fatty acid esters, ethers, hemi- acetais or acetals of polyhydroxylic compounds, are used as the main emulsifier, the amount used will typically be from about 0.2% to about 1.2%, more usually from about 0.3% to about 1%, particularly from about 0.4% to 0.8%, by weight of the emulsion.

It is generally technically possible to freely combine non-ionic emulsifiers of the alkoxylate and non-alkoxylate types described above. Such combinations may be attractive where the emulsifier system includes a hydrophilic alkoxylate emulsifier, eg using a low HLB non-alkoxylate emulsifier in combination. However, hydrophilic non- alkoxylate emulsifiers, especially sugar mono-ester emulsifiers, are more expensive than typical alkoxylate emulsifiers and will usually be used only when it is desired to have an emulsifier stabiliser system which includes no derivatives of alkylene oxides.

The oil phase used will typically mainly be an emollient oil of the type widely used in personal care or cosmetic products. The emollient oil can and usually will be an oily material which is liquid at ambient temperature.

Suitable normally liquid emollient oils include non-polar oils, for example mineral or paraffin, especially isoparaffin, oils, such as that sold by Croda as Arlamol™ HD; or medium polarity oils, for example vegetable glyceride oils such as jojoba oil, animal glyceride oils, such as that sold by Croda as Estol™ 3609 (triethylhexanoin), capylic/capric triglycerides, synthetic oils, for example synthetic ester oils, such as isopropyl isostearate, glyceryl isostearate and propylene glycol isostearates sold by Uniqema as Prisorine™ 2021 Prisorine™ 2034and Prisorine™ 2040 respectively, C₁₂ - C|₅ alkyl benzoatesor ether oils, particularly of two fatty e.g. C₈ to C₁₈ alkyl residues, such as that sold by Henkel as Eutanol G (octyl dodecanol), or silicone oils, such as dimethicione oil such as those sold by Dow Corning as DC2, cyclomethicone oil as sold by Dow Coming as DC245, or silicones having polyoxyalkylene side chains to improve their hydrophilicity; or highly polar oils including alkoxylate emollients for example fatty alcohol propoxylates such as that sold by Croda as Arlamol™ E (stearyl alcohol 15-propoxylate) or alkyl carbonates such as Cetiol CC (INCI: Dicaprylyl Carbonate) ex-Cognis. When non-polar oils are used it may be desirable to use relatively high concentrations of emulsifier, particularly high HLB emulsifier, in order to achieve suitably satisfactory emulsification, particularly to obtain small oil droplets. Mixtures of emollient oils can and often will be used and in some cases solid emollient oils may dissolve wholly or partly in liquid emollient oils or in combination the freezing point of the mixture is suitably low. Where the emollient oil composition is a solid at ambient temperature, the resulting dispersion may technically not be an emulsion (although in most cases the precise phase of the oily disperse phase cannot readily be determined) but such dispersions behave as if they were true emulsions and the term emulsion is used herein to include such compositions.

Many other components may be included in the emulsion compositions of the invention to make personal care or cosmetic formulations. These components can be oil soluble, water soluble or non-soluble. Examples of such materials include: preservatives and antimicrobials such as those based on parabens (alkyl esters of 4-hydroxybenzoic acid), phenoxyethanol, substituted ureas and hydantoin derivatives, eg those sold commercially under the trade names Germaben Il Nipaguard BPX and Nipaguard DMDMH, isothiazolinones e.g. Kathon CG and Neolone 950 sold by

Rohm and Haas, iodopropynyl butylcarbamate e.g. Glycacil 2000 sold by Lonza Inc., may be used usually in a concentration of from as low as about 5 ppm to 2% by weight of the emulsion depending upon the product and associated regulatory permitted levels of use; - perfumes, when used typically at a concentration of from 0.1% to 10% more usually up to about 5% and particularly up to about 2% by weight of the emulsion; humectants or solvents such as alcohols, polyols such as glycerol and polyethylene glycols, when used typically at a concentration of from 1 % to 10% by weight of the emulsion; sunfilter or sunscreen materials including chemical sunscreens and physical sunscreens including those based on titanium dioxide or zinc oxide; when used typically at from 0.1% to 5% by weight of the emulsion (but noting that physical sunscreen materials are often dispersed using acrylic polyanionic polymers that may tend to destabilise the emulsions because they supply electrolyte); alpha hydroxy acids such as glycolic, citric, lactic, malic, tartaric acids and their esters and salts; self-tanning agents such as dihydroxyacetone; vitamins and their precursors including: a) Vitamin A eg as retinyl paimitate and other tretinoin precursor molecules, b) Vitamin B eg as panthenol and its derivatives, c) Vitamin C eg as ascorbic acid and its derivatives, d) Vitamin E eg as tocopheryl acetate, e) Vitamin F eg as polyunsaturated fatty acid esters such as gamma-linolenic acid esters; botanical extracts such as Aloe Verawith beneficial skin care properties

The emulsions made in accordance with the invention can be used, as described above, as cosmetic or personal care products in themselves or can be fabricated into such products. For example, the emulsions of the invention may be used in spray applications, as body moisturisers, and in sun screen applications. In particular, the emulsions can be used to impregnate wipe substrates as hereinbefore discussed. Such wipe substrates may be made from natural or synthetic materials both woven or non-woven, or combinations of such materials and/or combinations of both woven and non-woven layers. Natural materials include cellulose fibres and synthetic materials include fibres made from polyolefins, polyesters, rayon, polyamides, polyesteramides, polyvinyl alcohols or mixtures or two or more thereof. Preferred wipe substrates are selected from non-woven synthetic fibre based materials.

For application to wipe substrates, the emulsions made using the invention will typically contain a relatively low proportion of oil phase typically from 1% to 10%, preferably from 2% to 5%, more usually about 3% by weight of the emulsion. The amount of emulsion impregnated into wipe substrates will depend on the desired properties in the end product, but will typically be from 100 to 1000 g m^"2 of wipe substrate. The wipe substrates will typically have a base weight of from 30 to 100 g m-². The wipes made using the invention may be used in cleansing applications such as personal hygiene and to remove make up or other cosmetics, for example.

Skin cleansing is a personal hygiene problem not always easily solved. Dry tissue products are the most commonly used cleansing products post-defecation or post- urine release. Dry tissue products are usually referred to as "toilet tissue" or "toilet paper". As an alternative or accompaniment to the use of dry tissue, the use wet wipes for the purpose of cleaning the anus, the perinea, and the peri-anal body area after defecation is becoming increasingly popular to minimise common hygienic concerns. The use of such wipes is babies, children and adults.

Among those negatives associated with the failure of adequate cleansing are irritation, redness, desquamation, infections, unpleasant odor or other kinds of personal discomfort or health related issues.

People suffering from pathological conditions (such as hemorrhoids, fissures, cryptitis, etc.) are even more susceptible to those issues and discomfort. For them, as for any persons, cleansing must be efficient in terms of removal of fecal residues and gentle in terms of absence of irritation caused by the cleansing. Wet-wipes bring a response to that basic need.

In comparison to dry toilet paper, wet wipes have several benefits, including: - lubrication during the use of the wipe with a consequent reduction in the abrasiveness of the cleansing operation; the softening and/or hydration of the residues, enhancing their removal from the skin; the hydration of the skin tissue; and - the ability to deliver a soothing lotion to the skin that can remain on the skin after the cleansing operation.

Emulsions made using the invention are also particularly effective in removing make up or other cosmetic preparations and can be as efficient as the neat oil in removing oily make up e.g. mascara, particularly "waterproof mascara". This is a surprising result as such emulsions in this use typically do not contain very high proportions of oil, typical amounts would be from 1% to 10%, more usually from 2% to 5% by weight of the emulsion.

In wipe applications, the emulsions may be formulated with additional components such as fragrances, soothing agents, preservatives, rheology modifiers, moisturisers, texturers, colourants, medically active ingredients such as skin protection ingredients and healing promoters, and combinations thereof.

Preferred emollient oils used in wipe applications are silicone oils, synthetic ester oils and vegetable glyceride oils as described above. Preferred emulsifiers used in wipe applications are alkoxylates, particularly C₁₆-C₁₈ ethoxylates, particularly using a 2 mole ethoxylate as the low HLB component and a >20 mole ethoxylate (particularly a 100 mole ethoxlyate) as the high HLB component.

Preferred soothing agents, ie compounds that have the ability to reduce the irritation or stinging/burning/itching effect of some chemicals, in addition to any soothing effect generated by the emollient oil selected, may include paraben-based preservative systems, antioxidants, buffer compounds and surfactants. Preferred soothing agents are (a) ethoxylated surface active compounds, more preferably those having an ethoxylation number below about 60; (b) polymers, more preferably polyvinylpirrolidone (PVP) and/or N-vinylcaprolactam homopolymer (PVC); and (c) phospholipids, more preferably phospholipids that are complexed with other functional ingredients as e.g., fatty acids, organosilicones. Most preferably the soothing agents of the present invention are selected from PEG40 hydrogenated castor oil, sorbitan isostearate, isoceteth-20, sorbeth-30, sorbitan monooleate, coceth-7, PPG-1 PEG-9 lauryl glycol ether, PEG-45 palm kernel glycerides, PEG-20 almond glycerides, PEG-7 hydrogenated castor oil, PEG-50 hydrogenated castor oil, PEG-30 castor oil, PEG-24 hydrogenated lanolin, PEG-20 hydrogenated lanolin, PEG-6 caprylic/capric glycerides, PPG-1 PEG-9 lauryl glycol ether, lauryl glucoside polyglyceryl-2 dipolyhydroxystearate, sodium glutamate, polyvinylpyrrolidone, N- vinylcaprolactam homopolymer, sodium coco PG-dimonium chloride phosphate, linoleamidopropyl PG-dimonium chloride phosphate, sodium borageamidopropyl PG- dimonium chloride phosphate, N linoleamidopropyl PG-dimonium chloride phosphate dimethicone, cocamidopropyl PG-dimonium chloride phosphate, stearamidopropyl PG-dimonium chloride phosphate and stearamidopropyl PG-dimonium chloride phosphate (and) cetyl alcohol and combinations thereof.

Preferred preservatives are those sold under the trade names Phenonip ex-Clariant a combination of Nipaset and Phenoxetol ex-Clariant and sodium benzoate and EDTA and its sodium salts.

The present invention also includes a wipe as herein described and an article of commerce comprising a container housing one or more wet wipes according to the invention.

The emulsifier and the polysaccharide emulsion stabiliser components used in the invention can be blended to provide a dry formulation that can be dispersed directly in water or in a polar emollient oil or in the non-aqueous liquid medium for subsequent combination with the emollient oil. Typically, these dry formulations include the solid components including the emulsifier and polysaccharide emulsion stabiliser. For such formulations, it is useful to use both high HLB and low HLB emulsifiers.

Preferably, the dry blended product is desirably a powder having a mean particle size of from about 100 to about 500 μm to facilitate dispersion of it in the liquid medium. To facilitate handling, eg to reduce the risk of powder combustion, the powder desirably contains little or no material having a much lower particle size. In particular, the proportion of particles of size lower than 50 μm is less than 10% (by weight), desirably less than 2%, particularly less than 1%. Alternatively, the emulsifier and the polysaccharide emulsion stabiliser components used in the invention may be added separately to water or a polar emollient oil or in the non-aqueous liquid medium for subsequent combination with the emollient oil.

The present invention will now be further described by way of illustration only with reference to the following Examples. Examples

The materials used in the Examples were as follows:

Emulsifiers - Brij™ 72 (Steareth-2) and Brij™ 700 (Steareth-100), available from Croda.

Polysaccharide emulsion stabiliser materials - Keltrol F (food grade Xanthan gum ex Kelco) and a commercially-available polyglucomannan gum ("Mannan Gum").

Pre-formulated emulsifier/polysaccharide emulsion stabiliser - a pre-formulated emulsifier and polysaccharide powder available as Arlatone V-150™ available from Croda. Arlatone V-150™ material contains Steareth-100, Steareth-2, Xanthan Gum and Mannan Gum. In the formulation, the weight ratio of the Xanthan Gum to Mannan Gum is 1:1.

Propylene glycol - available from BDH (solubility parameter 31).

Pricerine™ 9091 - glycerine available from Uniqema (solubility parameter 38).

Estol™ 3609 - triethylhexanoin oil available from Croda (solubility parameter 20.42).

Prisorine™ 2021 - isopropyl isosterate oil available from Uniqema (solubility parameter 17.66).

Prisorine™ 2034 - propylene glycol isosterate oil available from Uniqema (solubility parameter 19.54). Nipasept - methylparaben, ethylparaben, propylparaben available from Clariant. Sodium benzoate.

Disodium ethylene diamine tetra-acetic acid (disodium EDTA). Titriplex III - EDTA Example 1 (Comparative)

At ambient temperature, two emulsions (Comparative Samples 1 and 2) were made by adding for each emulsion propylene glycol (1.0 wt%, 4.Og) to a 600 ml tall glass beaker and then adding Arlatone V-150™ material (0.3 wt%, 1.2g) to the beaker to disperse it in liquid phase by stirring at 300 rpm using a paddle stirrer having six blades (50mm) diameter.

Emollient oil consisting of a mixture of Estol™ 3609 oil (1.5 wt%, 6.Og) and Prisorine™ 2021 oil (1.5 wt%, 6.Og) (solubility parameter of the mixture was 19.04) was then added to the mixer.

Water (95.2 wt%, 380.8g) containing Nipasept material (0.2 wt%, 0.8g), sodium benzoate (0.2 wt%, 0.8g) and Titriplex III material (0.1 wt%, 0.4g), was added slowly to the mixer during stirring until phase inversion occurred to form an oil-in-water emulsion, following which the remaining water was added at a faster rate.

The mixer was operated (approximately 10 minutes) at 300 rpm to attempt to homogenise the mixture; however, the oil phase immediately separated out at the top of the water in both samples.

The procedure was repeated to produce Comparative Samples 3 to 6, except that the Nipasept material was added to the propylene glycol and no Titriplex III material was used. The quantities of materials used are shown in Tables 1 and 2.

The mixer was operated (approximately 10 minutes) at 300 rpm to attempt to homogenise the mixtures; however, the oil phase immediately separated out at the top of the water in both Comparative Samples 3 and 4 and after 24 hours in Comparative Sample 5 with Comparative Sample 6 was creaming after 24 hours. Table 1

Table 2

Example 2

An oil phase was made by mixing Prisorine™ 2021, Prisorine™ 2034 and Estol™ 3609 oils at ambient temperature in a 600 ml tall glass beaker and then adding Brij™ 700 material (0.22 wt%, 0.88g) and Brij™ 72 material (0.08 wt%, 0.32g) to the beaker. As the Brij™ 700 and Brij™ 72 materials were bulk materials rather than powders, the mixture was then heated to >55°C to melt those materials into the oil phase. The mixture in the beaker was then returned to room temperature. Ketrol F gum (0.13 wt%, 0.52g) and Mannan gum (0.02 wt%, 0.08g) were then added to the beaker and stirred into the mixture to disperse the gums therein. A mixture of water (5.05 wt%, 20.2Og) and Pricerine™ 9091 material (1.50 wt%, 6.0Og) was then slowly added whilst stirring (500 rpm) to phase invert the mixture in the beaker. The mixture was stirred for about a further 10 minutes until it was uniform.

The bulk of the remaining water (85 wt%, 34Og) was then added to the beaker followed by an aqueous solution of sodium benzoate (0.20 wt %, 0.8Og) and disodium EDTA (0.10 wt%, 0.4Og) (water 4.70 wt%, 18.8Og). Stirring continued for a further 10 minutes until the mixture was homogenised. This resulted in a stable emulsion suitable for use in wet wipe applications. The gum ratio was 6.5:1 , weight 0.15% and the sodium benzoate was present at 0.006M.

Example 3

Ketrol F gum (0.13 wt%, 0.52g) and Mannan Gum (0.02 wt%, 0.08g) were premixed with Pricerine™ 9091 material (1.50 wt%, 6.0Og) and then added to water (89.3%, 357.2Og) with stirring and heated to 75 to 90⁰C. Once the gums had completely dispersed, Brij™ 700 material (0.22 wt%, 0.88 g) and Brij™ 72 material (0.08 wt%,

0.32g) were added and stirring continued.

In a separate container, an oil phase was made by mixing Prisorine™ 2021 (1.5 wt%,

6.0Og) and Estol™ 3609 (1.5 wt%, 6.0Og) oils. The water phase was slowly added to the oil phase until inversion occurred, after which the remaining water phase was added more quickly.

Finally, an aqueous solution of sodium benzoate (0.20 wt%, 0.8Og) and disodium

EDTA (0.10 wt%, 0.4Og) in water (4.70 wt%, 18.8Og), and Nipasept material (0.25 wt%, 1.0g) premixed with propylene glycol (0.50 wt%, 2.Og) were added. Stirring was continued for a further 10 minutes until the mixture was homogenised.

The emulsion was stable for at least 3 months at room temperature, 40⁰C, 50⁰C and temperature cycling at -5/4O⁰C, and was particularly suitable for use in wet wipe applications.

Claims

1. An oil-in-water emulsion comprises 1% to 10% by weight of the emulsion of a discontinuous oil phase, at least an effective amount of oil emulsifier, and 0.05% to 0.25% by weight of the emulsion of a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1 , and at least an effective amount of at least one electrolyte.

2. An emulsion according to claim 1 which comprises at least 0.1% by weight of the emulsion of the polysaccharide emulsion stabiliser.

3. An emulsion according to any one of claims 1 and 2 which comprises not more than 0.2% by weight of the emulsion of the polysaccharide emulsion stabiliser.

4. An emulsion according to any one of the preceding claims wherein the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is at least 2:1 and more especially is at least 4:1.

5. An emulsion according to any one of the preceding claims wherein the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is not more than 100:1 and is more preferably not more than 50:1 and more especially is not more than 20:1.

6. An emulsion according to claim 5 wherein the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is not more than 15:1 and is especially not more than 12:1.

7. An emulsion according to any one of the preceding claims wherein the minimum amount of emulsifier is 0.05% by weight of the emulsion.

8. An emulsion according to any one of the preceding claims wherein the amount of emulsifier is not more than 1.5% by weight of the emulsion, more preferably not more than 1% by weight of the emulsion and especially not more than 0.5% by weight of the emulsion.

9. An emulsion according to any one of the preceding claims wherein the amount of electrolyte is not greater than 0.05 molar, desirably not more than

0.02 molar and particularly not more than 0.01 molar.

10. A wipe comprises a wipe substrate impregnated with an oil-in-water emulsion, said emulsion comprising 1% to 10% by weight of the emulsion of a discontinuous oil phase, at least an effective amount of oil emulsifier, and 0.05% to 0.25% by weight of the emulsion of a polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1 , and at least an effective amount of at least one electrolyte.

11. A wipe according to claim 10 wherein the weight ratio of the Xanthan polysaccharide to the polyglucomannan polysaccharide is at least 2:1 and more especially is at least 4:1.

12. A wipe according to any one of claims 10 and 11 wherein the amount of electrolyte is not greater than 0.05 molar, desirably not more than 0.02 molar and particularly not more than 0.01 molar.

13. An emollient oil composition comprising emollient oil in which is dispersed at least an effective amount of oil emulsifier based on the composition of a final oil-in-water emulsion made from the emollient oil composition and 0.05% to 0.25% by weight of a final oil-in-water emulsion made from the emollient oil composition of a polysaccharide emulsion stabiliser wherein said polysaccharide emulsion stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1.

14. An emollient oil composition comprising emollient oil and a non-aqueous liquid medium with a Hansen and Beerbower solubility parameter of at least

19 but less than 45 in which is dispersed an effective amount of an oil emulsifier and a polysaccharide emulsion stabiliser wherein said polysaccharide emulsion stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1:1.

15. A composition according to any one of claims 13 and 14 in which the emollient oil has a Hansen and Beerbower solubility parameter of less than 19.

16. A composition according to any one of claims 13 and 14 in which the emollient oil has a Hansen and Beerbower solubility parameter of at least 19 but less than 45.

17. A composition according to any one of claims 13 to 16 which comprises 1% to 10% by weight of oil and, when present, non-aqueous liquid medium, based on a final emulsion made from the composition, between 45% and 80% by weight of water, an effective amount of electrolyte and, optionally, other additives.

18. An aqueous composition comprising (i) water, (ii) at least 0.5% by weight of polysaccharide emulsion stabiliser, which stabiliser comprises a Xanthan polysaccharide and a polyglucomannan polysaccharide in a weight ratio of greater than 1 :1 ; (iii) at least 5% by weight of polyol; and optionally (iv) at least 1 % by weight of emulsifier.

19. An article of commerce comprising a container and, contained therein, a wipe according to any one of claims 10 to 12.