GB2560209A

GB2560209A - High internal phase emulsions

Info

Publication number: GB2560209A
Application number: GB1712154.2A
Authority: GB
Inventors: Mary Recardo Caroline
Original assignee: Alchemy Ingredients Ltd
Current assignee: Alchemy Ingredients Ltd
Priority date: 2017-07-28
Filing date: 2017-07-28
Publication date: 2018-09-05
Anticipated expiration: 2037-07-28
Also published as: WO2019020778A1; GB201712154D0; GB2560209B

Abstract

An emulsifying composition for forming a water-in-oil high internal phase emulsion comprising at least one polyglycerol ester, at least one sorbitan ester, and at least one emollient ester. Water-in-oil high internal phase emulsion formed using the emulsifying composition and a method of making the water-in-oil high internal phase emulsion are also claimed. The formed emulsion is at least 75% internal phase by weight. Preferably the composition contains less than 1% silicone oil. In an embodiment, the emulsion contains a wax with a melting point of 50°C or more. The internal phase may also comprise glycerine and a soluble metal salt. Pigments, fragrances, dyes and/or pharmaceutical actives may be incorporated into the emulsion. The internal and external phases are mixed at between 15-25°C. In a preferred embodiment, the internal phase contains glycerine, squalane, MgSO4 and water whilst the external phase comprises polyglycerol-3-dioleate, sorbitan sesquioleate and isopropyl palmitate.

Description

(54) Title of the Invention: High internal phase emulsions Abstract Title: High internal phase water-in-oil emulsions (57) An emulsifying composition for forming a water-in-oil high internal phase emulsion comprising at least one polyglycerol ester, at least one sorbitan ester, and at least one emollient ester. Water-in-oil high internal phase emulsion formed using the emulsifying composition and a method of making the water-in-oil high internal phase emulsion are also claimed. The formed emulsion is at least 75% internal phase by weight. Preferably the composition contains less than 1% silicone oil. In an embodiment, the emulsion contains a wax with a melting point of 50°C or more. The internal phase may also comprise glycerine and a soluble metal salt. Pigments, fragrances, dyes and/or pharmaceutical actives may be incorporated into the emulsion. The internal and external phases are mixed at between 15-25°C. In a preferred embodiment, the internal phase contains glycerine, squalane, MgSO₄and water whilst the external phase comprises polyglycerol-3-dioleate, sorbitan sesquioleate and isopropyl palmitate.

Figure 1

1/1

High Internal Phase Emulsions

This invention relates to a composition suitable for forming a high internal phase emulsion, high internal phase emulsions formed therefrom and methods of forming high internal emulsions. The invention particularly relates to compositions formed from natural ingredients and in particular to compositions formed from vegetable oil components.

There are many different products which are designed to be applied to the skin, including creams, liquids and gels. For many cream or gel products, an important factor is the rheological profile of the product. It is common to use products which have a non-Newtonian rheological profile (products which are thixotropic or pseudoplastic). Such products do not run when in packaging and so are easy to handle, but spread easily on the skin’s surface when spreading force is applied.

These desirable rheological characteristics can be achieved in a number of different ways. It is important that the rheology remains stable throughout the lifetime of the product. One standard method in the field is to use an oil-in-water emulsion. Such emulsions are commonly stabilised using an emulsifier and a water structuring agent such as carbomer or a natural gum.

Another common type of emulsion that can be used is a water-in-oil emulsion, which is again stabilised using an emulsifier. One such emulsifier for use in water-in-oil emulsions is commercially available as Neocare P3R from Gova Research. This emulsifier is formed from a mixture of polyglyceryl-3 polyricinoleate and polyglyceryl-3 ricinoleate and has a hypophile-lipophile balance (HLB) of 3.5.

An alternative emulsion which has excellent rheological properties is a high internal phase emulsion. A traditional emulsion is formed of a large external phase and a smaller internal phase in which droplets of the internal phase are surrounded by a surfactant and suspended in the external phase. In a high internal phase emulsion (HIPE), the external phase forms a small part of the emulsion. This emulsion is formed by allowing distortion of the droplets in the internal phase from a spherical shape to a polyhedral shape. This distortion is only obtainable by careful selection of specific emulsifier systems. The polyhedral shape of the droplets allows the internal phase to be present in an amount of up to 99% of the total volume of the emulsion. By comparison, for standard packing of spherical particles, the internal phase can be a maximum of approximately 74% of total volume of the emulsion. Therefore, a HIPE according to the present application is an emulsion in which the volume of the internal phase is at least 75% of the total volume of the emulsion. It is preferred that the internal phase forms at least 80% of the total volume of the emulsion. Preferably the internal phase forms less than or equal to 95% of the total volume of the emulsion. Where the internal phase is greater than 95%, in some cases the emulsion can become too thick to handle easily and lies outside the preferred viscosity of a cosmetic preparation, which is generally between 500 and 100,000 cps. HIPEs are particularly suitable for use for products to be applied to the skin as they have a suitable rheometry but do not require the use of additional water thickeners as is the case in oil-in-water emulsions. Water-in-oil emulsions also usually have a low viscosity. In order to thicken water-in-oil emulsions, an oil thickener is typically required in large quantities. Suitable thickeners include wax, Bentone Gel® and fumed silica. Disadvantages of using these thickeners in sufficient quantities to include making the resultant product too heavy and also too greasy.

In addition, as water-in-oil HIPEs contain low levels of oil, they are significantly less expensive to produce than conventional water-in-oil emulsions as the oils are more expensive than water.

However, HIPEs commonly do not have high levels of stability. In addition, commercially available HIPEs are commonly formed using silicone oils. Such emulsions are disclosed for example in KR20140070719 and US2003/0064046. Silicone-based oils are not suitable for manufacturers who are attempting to make “natural product” or “organic product” formulations i.e. formulations whose oils are based on natural products or organic products. Therefore, whilst silicone oils produce HIPEs with excellent properties, the resulting HIPEs are not suitable for many applications. For the purposes of this application, products which are defined as being an “organic product” or a “natural product” are those which comply with the COSMOS-standard as set out at www.cosmos-standard.org.

In addition, when producing HIPEs, there is a requirement to mix the oil and water in order to produce the emulsion. Typically, the mixing needs to be undertaken under high shear in order to obtain the phase shift.

Accordingly, it would be desirable to provide an emulsfiying composition for producing a water-in-oil high internal phase emulsion with high levels of stability. It would be particularly desirable if this composition was formed only using oils formed from natural products. It would be further desirable if it was possible to produce the emulsion without the need for high shear mixing. It would be additionally advantageous to produce the emulsion without the need for heating the reactants so that active ingredients can be included in either the oily phase or the aqueous phase before mixing.

In addition, it would be desirable to provide an oil-based organic composition which was suitable for forming high internal phase emulsions having the above desired properties. It would be further desirable if those high internal phase emulsions could be defined as being natural or organic according to the COSMOS definitions.

Accordingly, in a first aspect of the present invention, there is provided an emulsifying composition for forming a water-in-oil high internal phase emulsion comprising: at least one polyglycerol ester, wherein the polyglycerol ester has an HLB of from 2 to 7; at least one sorbitan ester; and at least one emollient ester.

Preferably, the polyglycerol ester has an HLB of from 2 to 5.5. It is preferred that the esters of the emulsifying composition are formed only from natural products or organic products as defined above. Preferably the esters can be considered as natural products as defined above. It is further preferred that all of the components of the composition are formed only from natural products or organic products.

It is preferred that the emulsifying composition contains less than 2 weight percent of silicone oils, preferably less than 1 weight percent, and most preferably does not contain any silicone oils.

Further, it is preferred that the composition is formed only of a mixture of natural esters.

In a second aspect of the present invention, there is provided a composition for producing a water-in-oil high internal phase emulsion comprising the emulsifying composition of the first embodiment and a wax having a melting point of at least 50°C. Preferably, the organic composition additionally comprises an emollient which is not an emollient ester.

In a third aspect of the present invention, there is provided a water-in-oil high internal phase emulsion comprising the emulsifying composition of the first aspect or the composition of the second aspect; a soluble metal salt and water.

In a fourth aspect of the present invention, there is provided a method of making a water-inoil high internal phase emulsion comprising mixing the emulsifying composition of the first aspect with water and a soluble metal salt, wherein the mixing is undertaken at a temperature of from 15 to 25°C. Preferably, the method comprises stirring the oily phase at low shear at room temperature and adding the aqueous phase in small increments. The skilled person understands what is meant by low shear mixing. It is preferred that the shear rate of the stirrer is approximately 500 to 2000 rpm and more preferably approximately 1000 rpm when using a mixer such as an I KA Eurostar 20 with a standard blade. Other similar mixers can be used to achieve the required low shear mixing. Once an initial emulsion has formed between the oil and the water, it is possible to add the aqueous phase more quickly.

The emulsifying composition of the present invention is one which can be mixed with water to produce a stable water-in-oil high internal phase emulsion. The composition can be mixed with other organic components prior to mixing with water in order to improve the stability of the resulting emulsion, to improve the feel of the resulting emulsion or for other reasons set out below.

The emulsifying composition forms a minor part of the resulting water-in-oil emulsion as the aqueous phase is the major part. It is preferred that the emulsifying composition comprises from 2 to 20 weight percent of the total HIPE, preferably from 3 to 12 weight percent and more preferably from 5 to 9 weight percent.

The emulsifying composition comprises at least one polyglycerol ester, at least one sorbitan ester and at least one emollient ester.

A polyglycerol ester is the product of a polyglycerol and one or more carboxylic acids. In the present invention, the polyglycerol preferably has an average of from 2 to 20 glycerine units, more preferably from 3 to 10 glycerine units and even more preferably from 3 to 6 glycerine units. It is particularly preferred that the ester has three glycerine units. The carboxylic acids are preferably naturally occurring carboxylic acids and it is preferred that the carboxylic acids are naturally occurring fatty acids. Preferably the carboxylic acids have from 8 to 22 carbon atoms, which is the length of carbon chains found in naturally occurring fatty acids in triglycerides. The fatty acids can be either linear or branched.

Both saturated and unsaturated fatty acids are suitable. However, unsaturated fatty acids are preferred.

One important feature of the polyglycerol esters is the HLB. It is a requirement that the HLB of the polyglycerol ester is from 2 to 7. It is a preferred that the HLB in the present invention that the HLB is from 2 to 5.5. Preferably, the HLB is from 2 to 4. It is further preferred that the HLB is from 2.5 to 3.5, and particularly preferred from 3 to 3.5. HLB values can either be calculated or determined experimentally. However, the standard methods of calculation, such as those of Griffin (Journal of the Society of Cosmetic Chemists 5 (1654): 259) or Davies (Gas/Liquid and Liquid/Liquid interface: Proceedings of the International Congress of the Surface Activity (1657): 426-438), are not sufficiently accurate for many types of materials. Therefore, the HLB values referred to in the present application are obtained experimentally. It is usual for suppliers of materials to provide HLB values for their products which are obtained experimentally. The skilled person is aware of suitable methods to determine the HLB value, such as using comparative testing by forming a series of emulsions with an emulsifier and an oil of known HLB value.

Suitable polyglycerol esters include polyglyceryl-3-dioleate, which has an average of 3 glycerine units and an average of 2 oleic acid residues per glycerine unit. Other suitable polyglycerol esters include polyglyceryl-6-isostearate and polyglyceryl-6-dioleate.

The polyglycerol ester is present in an amount of 5 to 75 weight percent of the emulsifying composition, preferably from 10 to 45 weight percent and more preferably from 12 to 25 weight percent.

The polyglycerol ester preferably forms from 0.5 to 3 weight percent of the total HIPE, more preferably from 1 to 1.5 weight percent.

The composition additionally comprises at least one sorbitan ester. A sorbitan ester is the reaction product of sorbitan and one or more carboxylic acids. Preferably the carboxylic acids have from 8 to 22 carbon atoms, which is the length of carbon chains found in naturally occurring fatty acids in triglycerides. Particularly preferred are carboxylic acids having from 16 to 22 carbon atoms and even more preferably having 18 carbon atoms. The fatty acids can be both linear and branched.

Some commercially available sorbitan esters which are suitable for use in the present invention include:

Trade Name	INCI	HLB
Glycomul™ TS KFG/Lonza	Sorbitan tristearate	2.1
Lonzest™ SMO /Lonza	Sorbitan oleate	4.3
Span 120/Croda	Sorbitan isostearate	4.7
Lonzest™ STO /Lonza	Sorbitan trioleate	1.8
Span 83 /Croda	Sorbitan sesquioleate	3.7

Suitable sorbitan esters have an HLB of less than 6.0. Preferred sorbitan esters are those having an HLB of less than 4.5. Particularly preferred is sorbitan sesquioleate. HLB values for the sorbitan esters are determined experimentally in the same manner as described above for polyglycerol esters.

The sorbitan esters cannot produce a HIPE as the sole component of the oily phase as they are incapable of distorting the internal phase droplets sufficiently. However, they are effective at stabilizing the water-in-oil HIPE. They are particularly effective at stabilizing the HIPE at lower temperatures (up to and including 40°C).

The at least one sorbitan ester is to be used in a total amount of from 1 to 50 weight percent of the emulsifying composition. It is preferred that the total amount of sorbitan ester is from 1 to 10 weight percent of the emulsifying composition, as at higher levels it can give the HIPE a heavy feeling and can make the HIPE less easy to rub in to skin. The sorbitan ester is more preferably present in an amount of from 2 to 6 weight percent and most preferably approximately 3 to 6 weight percent.

It is preferred that the sorbitan ester is present in the final HIPE in an amount greater than 0.1 weight percent, preferably greater than 0.15 weight percent. It is preferably present in an amount of less than or equal to 1 weight percent and preferably less than or equal to 0.5 weight percent.

The composition additionally comprises at least one emollient ester. The emollient esters advantageously act as a solvent for the other emulsifying components in the composition. In addition, they form a major part of the external oily phase. They additionally prevent the resulting HIPE from having too high a viscosity and help the texture of the final product. The emollient ester can be liquid or solid. An emollient ester therefore is one which forms part of the oily phase of the resulting HIPE and does not have any surface activity. The emollient ester is preferably the reaction product of an alcohol and a carboxylic acid in which there are no other polar groups such as ether groups in either the alcohol or the carboxylic acid.

It is preferred that the emollient ester is an ester based on a carboxylic acid of natural origins. Preferably, the ester is a reaction product of a carboxylic acid having from 8 to 22 carbon atoms or carbonic acid with an alcohol having from 3 to 22 carbon atoms.

Preferably, the carboxylic acid has from 12 to 18 carbon atoms. Preferably the alcohol has a chain length of from 3 to 12 carbon atoms and more preferably from 3 to 6 carbon atoms.

It is preferred that the total number of carbon atoms in the emollient ester is from 12 to 24.

Preferred carboxylic acids include carbonic acid, myristic acid, palmitic acid, stearic acid, caprylic acid and capric acid. Preferred alcohols include isopropanol, ethylhexanol, octyldodecanol and coconut alcohol (a mixture of alcohols including caprylyl alcohol, capryl alcohol, lauryl alcohol and stearyl alcohol produced from coconut oil which is commercially available).

Particularly preferred esters include isopropyl myristate; isopropyl palmitate; dicaprylyl carbonate; octyldodecyl myristate; and coco-caprylate/caprate.

The emollient esters form a major part of the present composition. They are preferably present in the composition in a total amount of from 9 to 95 weight percent of the composition. It is preferred that the total amount of emollient esters is from 46 to 95 weight percent and more preferably from 65 to 90 weight percent.

One particularly preferred emulsifying composition comprises:

Material weight %

Isopropyl Palmitate 50-60

Isopropyl Myristate 20-30

Polyglyceryl-3 Dioleate 10-20

Coco-Caprylate/Caprate 2-8

Sorbitan Sesquioleate 2-6

A second particularly preferred emulsifying composition comprises:

Material weight %

Isopropyl Palmitate 65-75

Polyglyceryl-3 Dioleate 15-25

Coco-Caprylate/Caprate 2-8

Sorbitan Sesquioleate 2-6

The emulsifying composition can be mixed with other components to form a high internal phase emulsion.

The emulsion is typically produced by mixing an organic/oily phase with an aqueous phase.

The organic phase or oily phase comprises the emulsifying composition. In addition, it optionally comprises at least one other organic component. Preferred additional compounds are emollients other than the emollient esters which form part of the emulsifying composition.

The emollients are typically oils which help lower the viscosity of the HIPE, primarily by increasing the amount of oil in the external phase. The type and amount of oil used also have an impact on the texture of the HIPE.

Optional emollients include vegetable oils, squalane and silicone oils.

Where used, the emollients are selected to maintain the stability of the HIPE.

The emollients are preferably present in an amount of up to 30 weight percent of the oily phase. The additional emollients are present in an amount of from 0 to 5 weight percent of the total HIPE and more preferably from 0 to 2.5 weight percent, such as about 2 weight percent. It is further preferred that the emulsifying composition does not contain any additional emollients, with the only emollients being the emollient esters of the emulsifying composition.

Where silicone oils are used, it is preferable that they comprise less than 1 weight percent of the oily phase. It is preferred that silicone oils are not used.

In one preferred embodiment of the present invention, the oily phase additionally comprises at least one wax or butter.

Waxes and butters can improve the skin feel of the final HIPE, even at low levels (less than 0.5 weight % of the final HIPE). The waxes and butters can also improve high temperature stability of the HIPE. The total amount of wax or butter can be up to 2.5 weight percent of the final HIPE. However, it is preferred that the wax is used in a lower amount. It is preferred that a wax or butter is present in the final HIPE in an amount of from 0.25 to 1 weight percent and preferably from 0.5 to 0.75 weight percent of the final HIPE.

It is preferred that the butters or waxes have a melting point of at least 50°C and preferably a melting point of at least 60°C.

Suitable butters and waxes include sunflower wax, white beeswax, Kesterwax K82D, Dermofeel Viscolid, Cutina CP, BW Ester BW67, Acticire, rice bran wax, Cera Beilina, and Thixcin R.

Despite only being used in small quantities, it appears that the wax or butter is particularly advantageous at improving the stability of the HIPE at temperatures of 50°C. Whilst the HIPEs are rarely exposed to such temperatures in practice, it is considered that the testing of stability at 50°C shows some correlation with stability at lower temperatures. Therefore, it is advantageous, but not essential, for a HIPE to demonstrate stability at 50°C.

Other components which can be included in the oily phase include oil soluble components such as pharmaceutical actives, pigments, fragrances and dyes.

The aqueous phase can additionally contain a preservative. Suitable preservatives are known to the skilled person. Depending on the nature of the preservative, it may more soluble in the oily phase or the aqueous phase. For cosmetic formulations, Euxyl PE 9010 (a liquid preservative based on phenoxyethanol and ethylhexyglycerin) by SchCilke and Mayr GmbH is particularly suitable. This preservative is more soluble in the oily phase and so is added to the oily phase.

The aqueous phase primarily comprises water. The aqueous phase is present in an amount of at least 75% of the total volume of the resulting HIPE.

In combination with the emulsifying composition, water is the only essential component to produce a water-in-oil high internal phase emulsion. However, the stability of the emulsion is improved by the addition of other components.

In particular, in order to provide a HIPE with suitable stability, it is necessary to include one or more soluble metal salt. Preferred compounds are group 1 and group 2 metal salts, with group 2 metal salts being further preferred. Preferred counter ions include sulphates, carbonates and nitrates.

Magnesium sulphate is a particularly preferred metal salt.

Where present, the metal salt is used in an amount of from 0.2 to 2 weight percent of the total HIPE. Preferably, the metal salt is used in an amount of from 0.5 to 1.5 weight percent.

The metal salts act to help to partition the emulsifier into the interface, reducing the interfacial tension. This helps to improve the stability of the HIPE.

In addition to water, the aqueous phase can additionally include glycerine. The glycerine is present in an amount of from 0 to 10 weight percent of the total HIPE, preferably from 3 to 7 weight percent and more preferably approximately 5 weight percent. The glycerine provides a number of advantages in the final HIPE including improving the texture of the HIPE and also improving freeze thaw stability.

The aqueous phase can additionally contain a preservative. Suitable preservatives are known to the skilled person as discussed above. Where the preservative is more strongly hydrophilic, it is added to the aqueous phase rather than the oily phase.

The emulsion can be formed from the mixture of the oily phase and the aqueous phase. A third mixture can also be used. This mixture is used to introduce pigments, preservatives and fragrances into the HI PE, where these are not introduced in either the oily phase or aqueous phase. This mixture is typically added after the HI PE has been formed from the first two phases. In particular, where the oily phase contains a wax or butter, it is typically required to heat the mixture in order to form the HI PE. Where heating is required when forming the HIPE, it is preferred to use the third mixture to introduce the pigments, preservatives and fragrances to avoid them breaking down due to the heat.

The HIPE can also be used in pharmaceutical formulations. The active pharmaceutical ingredient can be introduced in any one of the three phases. However, it is preferably introduced in the third mixture.

It is preferred that the components of the third mixture are not heated, because this can cause the active ingredients, such as pharmaceutical, fragrance or pigment, to break down.

Where the method of formation does not involve heating, which is possible in the present application, it is possible to add the third mixture to either the aqueous phase or the oily phase prior to forming the HIPE.

Producing high internal phase emulsions usually requires high shear mixing in order to cause the phase inversion. However, the emulsifying composition of the present invention allows the formation of a HIPE without the need for high speed mixing or for heating of the components.

There are many advantages to being able to form a HIPE without using extreme mixing conditions. First, the method is more energy efficient and therefore less expensive to undertake. In addition, the preparation can be undertaken without the need for specialist high shear mixers and other safety equipment which results from the increased amount of aerosols which result from high shear mixing.

In addition, by using lower shear mixing, there is a reduced amount of risk of damaging the active ingredients either by excessive mixing or heating as part of the process.

Low and medium shear mixers are typically cheaper and more easily obtained. For example, it is possible to use general food mixers. This makes it easier for the HIPEs to be io produced on a smaller commercial scale from the emulsifying composition of the present invention.

Figures

The invention will be further described with reference to the drawings in which:

Figure 1 shows an image of a high internal phase emulsion according to the present invention measured using cryogenic transmission electron microscopy (cryo-TEM).

Examples

The following materials set out in Table 1 were used in producing the HIPEs of the Examples.

Table 1

Polyglycerol Ester	HLB	Manufacturer
Polyglyceryl-6 Isostearate	6	Gattefosse/Plurol Isostearique
Sucrose Stearate	16	Mitsubishi Kagaku Food Corporation/ Surfhope C1816
Sucrose Stearate	7	Mitsubishi Kagaku Food Corporation/ Surfhope C1807
Sucrose Laurate	16	Mitsubishi Kagaku Food Corporation/ Surfhope C1216
Polyglyceryl-6 Distearate	10	Gattefosse/Plurol Stearique
Polyglyceryl-6 Dioleate	5	Gattefosse/Plurol Oleique
Polyglyceryl-3 Diisostearate	4.5	Gattefosse/Plurol Diisostearique
Polyglyceryl Polyricinoleate	3-4	Dr. Straetmans 1 Dermofeel PGPR
Polyglyceryl-3 Dioleate	3	Gattefosse 1 Plural Oleique CC497

Sorbitan Ester
Sorbitan Sesquioleate		Croda 1 Span 83
Sorbitan Monostearate		Croda / Span 60
Emollient Esters

ll

Isopropyl Myristate		IQL/Waglinol 6014
Isopropyl Palmitate		IQL/Waglinol 6016
Caprylic/Capric Triglycerides		IQL1 Waglinol 3/9280
Ethylhexyl Stearate		BASF 1 Cetiol 868
Octyldodecyl Myristate		Gattefosse 1 MOD
Coco-Caprylate/Caprate		IQL/Waglinol 20080
Cetearyl Isononanonate		BASF/ Cetiol SN
Coco Caprylate		BASF 1 Cetiol C5
Ethylhexyl Palmitate		BASF 1 Cegesoft C24
Emollient
Lecithin		IFF Lucas Meyer / Emulmetik 300 IP
Squalane		Amyris 1 Neossance Squalane
Mineral Oil		Sonneborn 1 Benol
Dimethicone 350cs		Dow Corning 1 Dow Corning 200 Fluid 350cs

Wax/butter	INCI name
Sunflower wax	Helianthus Annus (Sunflower) Seed Wax	Koster Keunen
White Beeswax	Cera Alba	Koster Keunen
Kesterwax K82D	Di-C20-40 Alkyl Dimer Dilinoleate	Koster Keunen
Dermofeel Viscolid	Hydrogenated Vegetable Oil	Dr Straetmans
Cutina CP	Cetyl Palmitate	BASF
BW Ester BW67	Stearyl Beeswax (and) Behenyl Beeswax	Koster Keunen
Acticire	Jojoba Esters (and) Helianthus Annuus (Sunflower) Seed Wax (and) Acacia Decurrens Flower Wax (and) Polyglycerin-3	Gattefosse
Rice Bran Wax	Oryza Sativa (Rice) Bran Wax	Koster Keunen
Cera Beilina	Polyglyceryl-3 Beeswax	Koster Keunen
Thixcin R	Trihydroxystearin	Elementis


Aqueous Phase
Magnesium Sulphate		Reagent grade
Glycerine		Reagent grade
Water		Purified water

Other ingredients
Phenoxyethanol/Ethylhexylglycerin based preservative		Schulke and Mayr/ Euxyl PE 9010

Examples 1 to 4 and Comparative Examples 1 to 5

An emulsifying composition was made by mixing 1.5 parts by weight of an ester in accordance with Table 2 below and 5 parts by weight of isopropyl palmitate.

An aqueous composition was formed of 5 parts by weight of glycerine, 1 part by weight of magnesium sulphate and 87.5 parts by weight of water to make a total of 100 parts by weight.

An IKA Eurostar 20 overhead stirrer with an impeller head mixed the emulsifying composition at 1000 rpm. The aqueous composition was added slowly using a Pasteur pipette until one quarter of the mixture had been added. Subsequently, the aqueous composition was added in small portions of approximately 5% of the aqueous composition allowing the mixture to fully emulsify between additions.

Table 2 additionally shows the results of each mixture. It can be seen that only certain polyglycerol esters are capable of forming a HIPE. In addition, although some of the polyglycerol esters were capable of forming a HIPE, the quality and stability of the HIPE was variable.

Table 2

Example	Emulsifier	HLB	Outcome
CE1	Polyglyceryl-6 Isostearate	6	When water gets above approx. 50% of formula, an o/w emulsion is formed.
CE2	Sucrose Stearate	16	When water gets above approx. 50% of formula, an o/w emulsion is formed.
CE3	Sucrose Stearate	7	When water gets above approx. 50% of formula, an o/w emulsion is formed.
CE4	Sucrose Laurate	16	When water gets above approx. 50% of formula, an o/w emulsion is formed.
CE5	Polyglyceryl-6 Distearate	10	When water gets above approx. 50% of formula, an o/w emulsion is formed.
1	Polyglyceryl-6 Dioleate	5	Formed a HIPE with good texture. Was unstable at 50 degrees C and room temperature after a few hours.
2	Polyglyceryl-3 Diisostearate	4.5	Formed a HIPE, however texture was slightly rubbery.
3	Polyglyceryl Polyricinoleate	3-4	Did not form a HIPE on its own.
4	Polyglyceryl-3 Dioleate	3	Formed a HIPE with a good texture.

Example 5

Emulsifying compositions were produced using different amounts of sorbitan sesquioleate.

The emulsifying composition was produced by mixing amounts of sorbitan sesquioleate as set out in Table 3, 1.25 parts by weight of polyglyceryl-3-dioleate and 4.5 parts by weight of isopropyl palmitate.

The aqueous composition was formed from 5 parts by weight glycerine, 1 part MgSO₄ and a balance of water to form 100 parts by weight of resultant HIPE.

The emulsions were formed in the same manner as for Example 1 above.

The stability of the resultant HIPEs was measured by a visual inspection process and is shown in Table 3. The stability is recorded according to the following scale:

= perfect stability, no sign of leakage of water or separation at all = some very tiny signs of instability which may include an irregular surface, a few drops of water seen

3= product starting to break down, viscosity drop, water layer seen = 2 separate layers seen, visible separation = no cream visible, product lost viscosity, like water

A score of 1 is recorded as good, 2-3 as medium and 4-5 as poor.

Table 3

Amount of Sorbitan Sesquioleate	Stability 1 week	Stability 2 weeks	Stability 3 weeks
	RT	50°C	RT	50°C	RT	50°C
0 parts	Good	Poor	Good	Poor	Medium	Poor
0.1 parts	Good	Poor	Good	Poor	Medium	Poor
0.25 parts	Good	Medium	Good	Poor	Good	Poor
0.5 parts	Good	Medium	Good	Poor	Good	Poor

As can be seen, whilst it is possible to form a stable emulsion without the sorbitan ester or a 5 low amount of this ester, the resulting HI PE is not stable at room temperature up to three weeks or at 50°C after only a week.

Therefore, it is preferred that the sorbitan ester is present in the HI PE composition in an amount greater than 0.1 weight percent and preferably greater than 0.15 weight percent. From 0.25 to 0.75 weight percent is particularly preferred.

Example 6

Emulsifying compositions were produced using different emollient esters as set out in Table 4. Esters were selected on the basis of their availability, good spreading characteristics, and cost effectiveness.

The following composition formula was used:

Emollient ester

Polyglyceryl-3 Dioleate Sorbitan Sesquioleate Glycerine MgSO₄

Water as listed in Table 4 1.25 parts 0.25 parts 5 parts 1 parts to 100 parts

The emulsions were formed in the same manner as for Example 1 above.

Table 4

Ester used	parts in finished product	Result after making	Stability after 1 week at 50°C
Isopropyl Palmitate	4.5	Smooth, thick cream	Good
Coco-Caprylate/Caprate	4.5	Smooth, thick cream	Good
Dicaprylyl Carbonate	4.5	Smooth, thick cream	Good
Cetearyl Isononanoate	6.5	Very thick, needed to add an extra 2% of oil	Medium
Ethylhexyl Stearate	4.5	Very thick cream	Medium
Caprylic/Capric Triglycerides	4.5	Too thick to incorporate whole aqueous phase, adding more oil did not help.	N/A
Sunflower Oil	4.5	Too thick to incorporate whole aqueous phase, adding more oil did not help	N/A

The results show that the choice of emollient ester affects the thickness of the resulting HI PE and in some cases means that it is not possible to add as much water as is desirable.

Example 7

Different emulsifying compositions were produced using different blends of components to 10 test the stability of the resulting HIPEs at room temperature and 40°C for up to two weeks.

The compositions were mixed according to Table 5, with the components being given in parts by weight:

Table 5

Sample	A	B	C	D	E	F	G	H
Polyglyceryl-3 dioleate	1.5		1.5	1.25	1.25	1.25
Sorbitan sesquioeleate		1.5		0.25	0.25	0.25
Isopropyl palmitate	4.5	4.5		4.5		4.0	4.5	4.5
Coco-caprylate/caprate			4.5		4.5	0.5
Polyglyceryl-3 diisostearate							1.5
Polyglyceryl-6-dioleate								1.5
Isopropyl myristate	2	2	2	2	2	2	2	2

The oily phase was formed by mixing each of the above emulsifying compositions with Euxyl PE9010 preservative.

The aqueous phase was formed of 5 parts glycerine, 1 part MgSO₄ and a balance of water to form a HI PE of 100 parts by weight.

The emulsions were formed in the same manner as for Example 1 above. The HIPEs were formed at room temperature.

The HIPEs were tested for initial cosmetic acceptability based on a measure of the ease in 10 which the formulation can be rubbed into the skin on a scale of 1 to 5, with 1 being poor and being excellent. The HIPEs were also tested for stability both fresh and after ageing at either room temperature or 40°C. The stability of the HIPEs was defined as being either good, medium or poor as described above.

The results are set out below in Table 6.

Table 6

HIPE	Cosmetic acceptability	Stability
1 hour	3 days	1 week	2 weeks
			RT	40°C	RT	40°C	RT	40°C
A	4	Good	Good	Good	Good	Medium	Good	Poor
B	1	Poor	N/A	N/A	N/A	N/A	N/A	N/A
C	4	Good	Good	Good	Good	Medium	Good	Medium
D	4	Good	Good	Good	Good	Good	Good	Medium
E	4	Good	Good	Good	Good	Good	Good	Good
F	5	Good	Good	Good	Good	Good	Good	Good
G	4	Good	Medium	Poor	Medium	Poor	Medium	Poor
H	4	Good	Medium	Poor	Medium	Poor	Poor	Poor

Example 8

HIPE compositions were produced using different additional waxes or butters in the oily 5 phase.

The oily phase was produced by mixing the wax or butter in the amount set out in Table 8 with 2 parts by weight of isopropyl myristate, 0.5 parts by weight of preservative and 6 parts by weight of an emulsifying composition having the following components:

Isopropyl Palmitate 4.2

Polyglyceryl-3 Dioleate 1.14

Coco-Caprylate/Caprate 0.36

Sorbitan Sesquioleate 0.3

The wax or butter is added to the emulsifying composition and heated to slightly above its 15 melting point to form the oily phase.

The aqueous phase was formed by mixing 5 parts by weight of glycerine, 1 part by weight of magnesium sulphate and a balance of water to form 100 parts by weight of resultant HIPE. The aqueous phase was heated to the same temperature as the oily phase and added dropwise as described above.

The various waxes used are shown in Table 7.

Table 7

Example	Tradename	Melting point (°C)	Viscosity

1	Sunflower wax	75	100,600
J	White Beeswax	62	41,200
K	Kesterwax K82D	73	45,300
L	Dermofeel Viscolid	60	57,400
M	Cutina CP	46	40,000
N	BW Ester BW67	64	42,500
0	Acticire	77	56,300
P	Rice Bran Wax	79	95,800
Q	Cera Beilina	63	51,000
R	Thixcin R	85	75,900

The viscosity of the resultant HIPE using 0.5 weight percent wax was measured using a Brookfield Viscometer DV-E, spindle 94 at 10 rpm when measured at 25°C and shown in

Table 7.

The stability of the resultant HIPEs was measured at times up to 3 weeks. The results are shown in Table 8. These results demonstrated that whilst it is possible to form a stable HIPE using the emulsion composition of the present invention, the presence of a wax in the final

HIPE composition provides improved high temperature stability.

It can be seen that where the wax has a melting point of less than 50°C, the stability drops even at higher amounts of wax.

Table 8

Example

Stability 3 days 50 °C

Stability 1 week 50°C

Stability 2 weeks 50°C

Stability 3 weeks 50°C

0.25%

0.5%

1.0%

0.25%

0.5%

1.0%

0.25%

0.5%

1.0%

0.25%

0.5%

1.0%

I

Good

Medium

Good

Medium

Good

J

Good

Medium

Good

Poor

Medium

Good

K

Good

Medium

Good

Medium

Good

L

Good

M

Good

Medium

N

Good

Medium

Good

Medium

Good

Medium

Good

Ο

Good

P

Good

Q

Good

R

Good

Example 9

Emulsifying compositions were produced to test stability using combinations of glycerine,

MgSO₄, and wax as set out in Table 7.

The following composition formula was used:

Isopropyl palmitate	4.5 parts
Polyglyceryl-3 Dioleate	1.25 parts
Sorbitan Sesquioleate	0.25 parts
Isopropyl Myristate	2 parts
Polyglyceryl-3 beeswax	as in Table 9
Glycerine	as in Table 9
MgSO₄	as in Table 9
Water	to 100 parts

The emulsions were formed in the same manner as for Example 8 above.

Table 9

Formulation	Glycerine (parts)	MgSO₄ (parts)	Wax (parts)	Stability 1 week @ RT	Stability 1 week @ 50°C
1	0	0	0	Very Poor	Very Poor
2	5	0	0	Poor	Very Poor
3	0	1	0	Good	Medium
4	5	1	0	Good	Good
5	0	0	0.5	Poor	Poor
6	5	0	0.5	Poor	Poor
7	0	1	0.5	Good	Good
8	5	1	0.5	Good	Good

Emulsions can be formed in the absence of MgSO₄, glycerine and wax. However, the stability after a week is poor. It appears that the inclusion of the metal salt is particularly important to increasing the stability of the HIPE. Glycerine is less important for stability, but is useful for increasing heat stability and gives a better texture to the cream (better pick up, more shear thinning rheology).

Example 10

A high internal phase emulsion is formed using the following formulation:

Emulsifier composition 6%

Squalane 2%

Glycerine 5%

MgSO4 1%

Water 86%

The emulsifier composition used is formed from:

Polyglyceryl-3 Dioleate Sorbitan Sesquioleate Isopropyl palmitate

1.25%

0.25%

4.5%

The HIPE is formed using the same method as in Example 1.

The HIPE was then tested using cryogenic transmission electron microscopy (cryo-TEM). The results are shown in Figure 1.

The electron microscopy grid is first glow discharged and the sample of the HIPE applied. 10 As can be seen from Figure 1, the oily phase can be seen as a thin darker line between the aqueous areas. The droplets are not round but are distorted, which is typical of a HIPE.

Claims

1. An emulsifying composition for forming a water-in-oil high internal phase emulsion comprising:

at least one polyglycerol ester, wherein the polyglycerol ester has an HLB of from 2 to 7;

at least one sorbitan ester; and at least one emollient ester.

2. An emulsifying composition as claimed in claim 1, wherein the polyglycerol ester is the product of a polyglycerol having an average of from 2 to 20 glycerine units and at least one carboxylic acid having from 8 to 22 carbon atoms.

3. An emulsifying composition as claimed in claim 1 or claim 2, wherein the sorbitan ester is the product of sorbitan and at least one carboxylic acid having from 8 to 22 carbon atoms.

4. An emulsifying composition as claimed in claim 3, wherein the sorbitan ester has an HLB of up to 4.5.

5. An emulsifying composition as claimed in any one of the preceding claims, wherein the emollient ester is a mixture of two esters.

6. An emulsifying composition as claimed in any one of the preceding claims, wherein the at least one emollient ester is present in a total amount of from 46 to 95 weight percent.

7. An emulsifying composition as claimed in any one of the preceding claims, wherein the composition comprises less than 1% of a silicone oil.

8. An emulsifying composition as claimed in claim 7, wherein the composition does not contain any silicone oil.

9. A composition for producing a water-in-oil high internal phase emulsion comprising: the emulsifying composition of any one of claims 1 to 8; and a wax having a melting point of at least 50°C.

5

10. A composition as claimed in Claim 9, additionally comprising an emollient.

11. A water-in-oil high internal phase emulsion comprising: the emulsifying composition of any one of claims 1 to 8; and a soluble metal salt; and

10 water.

12. The emulsion of Claim 11, wherein the emulsion additionally comprises glycerine.

13. The emulsion of any one of Claims 11 to 12, wherein the emulsion additionally

15 comprises a wax having a melting point of at least 50°C.

14. The emulsion of any one of Claims 11 to 13, wherein the emulsion additionally comprises at least one of a pharmaceutical active, a pigment, a fragrance and a dye.

20

15. The emulsion of any one of Claims 11 to 14, wherein the emulsion does not contain any silicone oil.

16. A method of making an emulsion comprising mixing the emulsifying composition of any one of claims 1 to 8 with an aqueous phase comprising water and a soluble

25 metal salt, wherein the mixing is undertaken at a temperature of from 15 to 25°C.

Intellectual

Property

Office

Application No: GB1712154.2 Examiner: Miss Anna Crosby