EP0986369A1

EP0986369A1 - Surfactant compositions

Info

Publication number: EP0986369A1
Application number: EP98924470A
Authority: EP
Inventors: Marie Claire Leona Hilda Taelman; Christian Joseph Dederen; Katrin Stickdorn
Original assignee: Croda International PLC; Imperial Chemical Industries Ltd
Current assignee: Croda International PLC
Priority date: 1997-06-07
Filing date: 1998-05-28
Publication date: 2000-03-22
Also published as: GB9711786D0; AU7666898A; WO1998055088A1; JPH1112125A

Abstract

Organic solvent free co-polymeric surfactants of the formula: A - B - A where each A is an oligo- or polyester residue of a hydroxycarboxylic acid and B is a polyoxyalkylene chain (both as defined) are useful in personal care water-in-oil emulsion, particularly for emulsions where the aqueous phase includes dissolved electrolyte, urea or alcohols or for hydrophile-in-oil emulsions or dispersion having polyol or aqueous polyol solution hydrophile phase. The hydrophile-in-oil emulsions can be formulated as multiple hydrophile-in-oil-in-water emulsions. The invention includes a single step process for oil-in-water emulsions containing water-in-oil droplets by forming a mixture of an oil phase and oil-in-water primary (oil in water) emulsifier including also the copolymer surfactant and adding to the oil mixture under stirring to an aqueous phase. In particular the primary emulsifier is a combination of a hydrophilic fatty alcohol ethoxylate surfactant and a hydrophobic fatty alcohol ethoxylate surfactant and especially including added fatty alcohol.

Description

Surfactant Compositions

This invention relates to surfactant compositions and particularly to such compositions in which block copolymeric surfactants are used to disperse aqueous phases in oil phases in personal care products.

Polymeric surfactants are known for use in stabilising oil water interfaces, particularly in water-in-oil emulsions oil-in-water emulsions and dispersions. Such surfactants, include A-B-A block co-polymeric surfactants in which the A blocks are polyester blocks, particularly polyesters of hydroxy aliphatic acids e.g. of hydroxystearic acid to give polyhydroxy stearate (PHS) blocks, and the B block is a polyalkylene glycol block, especially a polyethylene glycol (PEG) block. Such surfactants are described in EP 0000424 and their use in stabilising the emulsion used in inverse emulsion acrylamide polymerisation in GB 2157744 and US 4776966. The molecules of these surfactants have a shape that makes them particularly useful in stabilising water-in-oil dispersions and emulsions. It is believed that, at the oil/water interface, the molecule sits with the hydrophilic PEG block in the water phase and the two hydrophobic PHS blocks in the oil phase. This arrangement gives good packing at the interface and is believed to contribute to the effectiveness of these materials. Originally, this type of surfactant was, manufactured by a process which used an organic solvent, typically xylene, so that the final product included trace quantities of the solvent that effectively precluded the use of these surfactants in skin contact applications. More recently, a variant of this type of surfactant has become available made by a method which does not involve the use of organic solvents such as xylene and this opens up the possibility of using such materials in personal care applications. These surfactants have proved to be useful water-in-oil dispersants and emulsifiers.

The present invention is based on our discovery that this type of surfactant can achieve particularly good results in certain types of formulation. In particular, in formulations including relatively high concentrations of solutes in a dispersed hydrophilic phase and in the manufacture of multiple emulsions by a particularly convenient route.

Accordingly the present invention provides a personal care composition which is or includes a hydrophile-in-oil emulsion or dispersion which includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where each group A is independently an oligo- or polyester residue of a hydroxycarboxylic acid, having a molecular weight of from 900 to 3000 Daltons (Da); and B is a polyoxyalkylene chain having a molecular weight of from 400 to 2500 Da, and in which the dispersed hydrophile phase is or includes dissolved therein one or more polyol, alcohol, electrolyte or urea.

The block group A is typically made up of repeat units of the formula:

- O - CH t(CH2)_a.CH3].(CH2)_b.COO- where a is typically from 3 to 8 and b is typically from 8 to 12 and a+b is typically from 11 to 17 (corresponding to overall carbon chain lengths in the precursor acid of 14 to 20). The repeat units in the blocks A are particularly desirably of 12-hydoxystearic acid i.e. where a is 5 and b is 10. Desirably, the number of fatty acid residues in each block A residues is on average from 3 to 10 (900 to 3000 Da), particularly from about 5 to about 8 (about 1500 to about 2400 Da) and especially about 7 (about 2100 Da).

In practice, such acids are commercially available as mixtures of the hydroxy acid and the corresponding unsubstituted fatty acid. Thus, 12-hydroxystearic acid is typically manufactured by hydrogenation of castor oil fatty acids including the C18 unsaturated hydroxy acid and the non-substituted unsaturated fatty acids (oleic and linoleic acids) which on hydrogenation gives a mixture of 12-hydroxystearic and stearic acids. During manufacture of the polyester chains, the presence of the unsubstituted acid acts to limit the chain length of the oligomer or polymer. Hydroxystearic acid is available containing about 15% unsubstituted stearic acid and this on polymerisation gives an average chain length of about 6 hydroxystearate residues terminated by a stearic acid residue.

The polyoxyalkylene chain is desirably a poiyoxyethylene chain and, in particular, it has a molecular weight of from about 400 to about 2000 Da and especially about 1500 Da.

A particularly useful material is the solvent free block copolymer polymeric surfactant sold by ICI Surfactants under the trade name Arlacel P135 which has a PEG residue with a molecular weight of about 1500, corresponding to about 34 ethylene oxide repeat units, and polyhydroxystearate residues each containing about 7 acid residues each, corresponding to a chain molecular weight of about 2100, and an overall molecular weight of about 5.5 to 6 kD

The oil phase used in the invention is typically an emollient oil which may be liquid or solid at ambient temperature. Suitable liquid emollient oils include non-polar oils such as mineral oils e.g. paraffin or /so-paraffin oils, and polar oils, particularly ester oils such as triglyceride oil e.g. vegetable oils or synthetic trigiycerides, synthetic ester oils ether oils silicone oils and alkoxylated oils. Suitable emollients that are solid at ambient temperature include emollient waxes such as paraffin waxes, ozokerite, beeswax and vegetable waxes e.g. castor wax and candelilla wax.

The oil phase may include other components such as essential oils, oil soluble vitamins, antioxidants, pigments, hydrophobic silica (such as Aerosil R972 ex Degussa), UVB and UVA sunscreen agents, and similar materials.

The hydrophile phase can be a solution in water of the hydrophilic material or can, in certain cases, be a substantially water free liquid phase of the hydrophilic material. Thus the invention includes:

1 a personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes dissolved therein at least one electrolyte, particularly where the electrolyte is aluminium and/or zirconium chlorohydrate, sodium chloride or a salt of an organic acids such as sodium lactate, and particularly at a concentration of from 0.1 to 25% by weight of the aqueous phase, and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where A and B are as defined above;

2 a personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes urea dissolved therein, particularly at a concentration of from 0.1 to 20% by weight of the aqueous phase, and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where A and B are as defined above;

3 a personal care composition which is or includes a hydrophile-in-oil emulsion or dispersion in which the dispersed hydrophile phase is a polyol or is water having a polyol dissolved therein, particularly glycerol, glycerol ethoxylated with from 1 to 100 moles of ethylene oxide, propylene glycol (1 ,2 propane diol), butylene and/or hexylene glycol, sorbitol, sorbitol ethoxylated with form 1 to 100 moles of ethylene oxide and polyethylene glycol (especially having a molecular weight distribution between 200 to 6000 Da with a typical average molecular weight of about 1500 Da), and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where A and B are as defined above; and

4 a personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes at least one alcohol dissolved therein, particularly in an amount of from 1 to 40%, and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where A and B are as defined above. In such systems the polymeric surfactant is typically used in an amount of 0.5 to 5%, more usually from 1 to 2%, by weight of the total emulsion.

Particularly for the hydrophile-in-oil emulsion (possibility 3 above) the system can be formulated as a multiple water-in-oil-in-water emulsion, by dispersing the hydrophile-in-oil emulsion in water, i.e. using conventional 2-step multiple emulsion manufacturing methods. Such double emulsions can contain from 30 to 90%, particularly from 50 to 80%, by weight based on the total multiple emulsion of the primary internal phase. Where the hydrophile is a glycol or glycerol, particularly where it is glycerol, the hydrophile phase may contain little if any water. This opens the possibility of making aqueous emulsions containing water sensitive materials, or materials that are sensitive to other environmental effects e.g. oxidation, in the presence of water, such as some water soluble vitamins especially vitamin C. The water sensitive material is dissolved in the hydrophile phase emulsified in an oil continuous phase and this emulsion is then emulsified into water or an aqueous phase.

The invention includes a method of making an oil-in-water emulsion containing water-in-oil droplets which includes forming a mixture of an oil phase and oil-in-water primary emulsifier for dispersing oil in an aqueous phase including also an oil soluble copolymer surfactant of the formula : A - B - A where A and B are defined as above, and adding to the oil mixture under stirring to an aqueous phase.

In forming in-situ multiple emulsions by this method it is necessary to include surfactants that promote the formation of the multiple emulsion i.e. act as a primary emulsifier for the oil droplets in the water. Suitable primary emulsifier surfactants are combinations of hydrophilic surfactants such as fatty alcohol, e.g. C₁₂ to C₂₂ fatty alcohols, ethoxylates having a high degree of ethoxylation e.g. an average of more than 15 ethoxylate residues per molecule, such as the hydrophilic ethoxylates supplied by ICI Surfactants under the trade designation Brij, particularly Brij 721 , Brij 78, Brij 98 and

Brij 99, and hydrophobic surfactants such as fatty alcohol, e.g. C₁₂ to C₂₂ fatty alcohols, ethoxylates having a low degree of ethoxylation e.g. an average of not more than 5, and usually not more than 3, ethoxylate residues per molecule, such as the hydrophobic ethoxylates supplied by ICI Surfactants under the trade designation Brij, particularly Brij 72, Brij 92 and Brij 93. Such combinations can form liquid crystal like phases at or near the oil-water interface and stabilise the oil droplets. The formation of these liquid crystal phases is enhanced by the inclusion of amphiphiles such as fatty alcohols, in particular C₁₂ to C₂₂ fatty alcohols, (in addition to any residual fatty alcohol which may be present especially in the hydrophobic component of the primary emulsifier) in the primary emulsifier. The relative amounts of hydrophilic surfactant and hydrophobic surfactant depend on the multiple emulsion system but are typically in the weight range 3:1 to 1 :5, particularly 1 :1 to 1 :2, especially about 1 :1.5. The relative weight of added fatty alcohol based on the combination of the hydrophilic and hydrophobic surfactants will usually be in the range 1 :10 to 1 :1 , more usually 1 :5 to 1 :2.

In general the multiple emulsion can be made by dissolving the hydrophobic and hydrophilic surfactants in the oil phase and adding the oil phase to the water phase under stirring. Conveniently this is done at moderately elevated temperatures e.g. between ambient temperature and 90°C, more usually between 70 and 85°C.

The amount of the polymeric surfactant used in making multiple emulsions in this way will typically be from 0.1 to 2% by weight of the total multiple emulsion. The amount of the primary emulsifier surfactant system (including any additional fatty alcohol) used is typically from 0.5 to 12%, particularly from about 3 to about 8% and especially from 5 to 7%, by weight of the total multiple emulsion.

This method has the practical advantage that only one emulsification step is needed in order to form a double/multiple emulsion, thus, thus simplifying and cheapening the production process. However, the method is restricted to such systems where the main external (aqueous) phase and the second internal (aqueous) phase are formed from the same aqueous phase, although post emulsification additions to the main external (aqueous) phase does enable the manufacture of systems where the two aqueous phases are not the same.

In the double emulsion made by this method, the oil phase can be similar to those described above. However, it is very desirable that the oil is a solvent for the polymeric surfactant to aid manufacture.

The following Examples illustrate the invention. All parts and percentages are by weight unless otherwise stated. Materials Arlacel P-135 solvent free PHS-PEG-PHS block copolymer ex ICI surfactants Arlamol HD /so-hexadecane emollient oil ex ICI surfactants Ariamol S7 propoxylated fatty alcohol and cyclomethicone ex ICI surfactants Arlamol M812 Capric/caprylic triglyceride emollient oil ex ICI surfactants Arlamol DOA Di-/so-octyl adipate emollient oil ex ICI surfactants Atlas G-2330 Sorbitol 30-EO ex ICI surfactants Brij 721 fatty alcohol 21 -ethoxylate ex ICI surfactants Brij 72 fatty alcohol 2-ethoxylate ex ICI surfactants Synperonic PE/F 127 EO-PO block copolymer ex ICI surfactants

Aerosil R972 Silica dimethylsilylate ex Degussa Oxynex K Antioxidant combination of PEG-8, tocopherol, ascorbyl palmitate, ascorbic acid and citric acid ex Merck

Florasun 90 Oil of Helianthus Annuus ex Floratech

Silbione Oil 70047V20 Dimethylpolysiioxane oil ex Rhone Poulenc

Hydroviton 2/059353 Aqeous solution of sodium lactate, lactic acid, glycerol, serine, sorbitol, TEA-lactate, urea, sodium chloride, lauryl diethyienediaminoglycerine, lauryl aminopropylglycerine, allantoin and denatured alcohol ex Dragoco

Nipaguard BPX A combination of phenoxyethanol, methylparaben propylparaben and 2-bromo-2-nitropropane-1 ,3-diol ex Nipa Keltrol Xanthan Gum ex Kelko

Example 1 Water-in-oil after-sun milk including ethanol in the internal phase.

The after-sum milk product was made by heating components A and B separately to 75°C, slowly adding B to A under intensive stirring, homogenising thoroughly for 1 minute. The emulsion was allowed to cool to 35°C under intensive stirring, component C was then added slowly and the product cooled to ambient temperature maintaining the intensive stirring. The product had a viscosity of 4450 mPa.s (Brookfield LVT, spindle C, 6 rpm) Example 2 Water-in-oil cleansing milk including glycerol and ethanol in the internal phase

The manufacturing procedure described in Example 1 was used. The product had a viscosity of 7880 mPa.s (Brookfield LVT, spindle C, 6 rpm)

Example 3

Water-in-oil antiperspirant cream

The water-in-oil antiperspirant cream product was made by heating components A and B separately to 75-80°C, slowly adding B to A under intensive stirring at ca 800 rpm (ca 170 Hz), homogenising thoroughly for 1 minute. The emulsion was allowed to cool to 50°C under intensive stirring, then component C was then added slowly and the product cooled to ambient temperature under stirring. The product had a viscosity of 50000 mPa.s (Brookfield LVT, spindle F, 6 rpm).

Example 4 Water-in-oil emulsion including natural oils and urea in the aqueous phase

The water-in-oil emulsion product was made by heating components A and B separately to 75, slowly adding B to A under intensive stirring, homogenising thoroughly for 1 minute, cooling under intensive stirring to 45°C, homogenising thoroughly for 1 minute and then cooling the product to ambient temperature under stirring. The product of Example 4a had a viscosity of 125580 mPa.s (Brookfield LVT, spindle F, 6 rpm) and that of Example 4b a viscosity of 116220 mPa.s (Brookfield LVT, spindle F, 6 rpm). The product of Example 4a was stable under accelerated storage testing conditions at 50°C for at least 1 week and the product of Example 4b was stable under accelerated storage testing conditions at 50°C for at least 1 month.

Example 5 Water-in-oil hydrating cream

The water-in-oil hydrating cream product was made by heating components A and B separately to 70°C, adding B to A under intensive stirring, homogenising thoroughly for 1 minute, cooling under stirring to 40°C, adding component C (urea dispersed in water) and homogenising the mixture thoroughly for 1 minute and then cooling the product to ambient temperature under continuous stirring. The product had a viscosity of 24160 mPa.s (Brookfield RDV1+, spindle 6, 6 rpm).

Example 6 Water-free cream

The water-free cream product was made by heating components A and B separately to 75°C, adding B to A under intensive stirring, homogenising thoroughly for 1 minute, cooling under moderate stirring to ambient temperature. The product had a viscosity of 130600 mPa.s (Brookfield RDVI+, spindle 7, 6 rpm)

Example 7 In-situ multiple emulsion

* see table below for the oils used

The in-situ multiple emulsion product was made by heating components A and B separately to 75°C, slowly adding A to B under moderate stirring, homogenising gently for 1 minute and cooling under intensive stirring to ambient temperature. Viscosity measurements made on a Brookfield LVT viscometer using spindle E, 6 rpm are included below).

Arlamol E 5.0 wt%; Arlamol HD 4.0 wt%.

Example 8

Two step glycerol-in-oil-in-water emulsion

The glycerol-in-oil-in-water emulsion product was made in two stages. The primary giycerol-in-oil emulsion was made by heating components A and B separately to 75°C, slowly adding B to A under intensive stirring, homogenising thoroughly for 1 minute and cooling under stirring to ambient temperature. The Secondary emulsion was made by forming component B' by dispersing the Synperonic PE/F 127 in the water at 5°C whilst stirring then adding the Nipaguard and slowly adding the primary emulsion (Component A') to B' under thorough stirring to form a multiple emulsion. Component C was made by slowly dispersing the Keltrol into the water under stirring and continuing stirring until a homogeneous gel is formed. Component C was gradually added to the multiple emulsion formed previously under gentle stirring. The product had a viscosity of 70000 mPa.s (Brookfield LVT, spindle E, 6 rpm).

Claims

1 A personal care composition which is or includes a hydrophile-in-oil emulsion or dispersion which includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A where each group A is independently an oligo- or polyester residue of a hydroxycarboxylic acid, having a molecular weight of from 900 to 3000 Daltons (Da); and B is a polyoxyalkylene chain having a molecular weight of from 400 to 2500 Da, and in which the dispersed hydrophile phase is or includes dissolved therein one or more polyol, alcohol, electrolyte or urea.

2 A composition as claimed in claim 1 in which the block group A is made up of repeat units of the formula: - O - CH [(CH2)_a.CH3].(CH2)_b.COO- where a is from 3 to 8; and b is from 8 to 12; and a+b is from 11 to 17.

3 A composition as claimed in claim 2 in which the block group A is residues of 12-hydoxystearic acid.

4 A composition as claimed in any one of claims 1 to 3 in which the number of fatty acid residues in each block A residues is on average from 3 to 10.

5 A composition as claimed in any one of claims 1 to 4 in which the polyoxyalkylene chain -B- is a poiyoxyethylene chain.

6 A composition as claimed in any one of claims 1 to 5 in which the polyoxyalkylene chain has a molecular weight of from about 400 to about 2000 Da.

7 A personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes dissolved therein at least one electrolyte and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A as defined in any one of claims 1 to 6.

8 A composition as claimed in claim 8 in which the electrolyte is aluminium and/or zirconium chlorohydrate, sodium chloride or a salt of an organic acid. A composition as claimed in either claim 7 or claim 8 in which the concentration of the electrolyte is form 0.1 to 25% by weight of the aqueous phase.

A personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes urea dissolved therein, which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A as defined in any one of claims 1 to 6.

A composition as claimed in claim 10 in which the concentration of the urea is from 0.1 to 20% by weight of the aqueous phase.

A personal care composition which is or includes a hydrophile-in-oil emulsion or dispersion in which the dispersed hydrophile phase is a polyol or is water having a polyol dissolved therein and which further includes as a block copolymeric surfactant of the formula: A - B - A as defined in any one of claims 1 to 6.

A composition as claimed in claim 12 in which the polyol is glycerol, glycerol ethoxylated with from 1 to 100 moles of ethylene oxide, propylene glycol (1 ,2 propane diol), butylene and/or hexylene glycol, sorbitol, sorbitol ethoxylated with from 1 to 100 moles of ethylene oxide and polyethylene glycol having an average molecular weight of from 200 and 6000 Da.

A composition as claimed in either claim 12 or claim 13 which is formulated as a multiple water-in-oil-in-water emulsion.

A personal care composition which is or includes a water-in-oil emulsion or dispersion in which the dispersed water phase includes at least one alcohol dissolved therein and which further includes as a dispersant and/or emulsifying agent a block copolymeric surfactant of the formula: A - B - A as defined in any one of claims 1 to 6.

A composition as claimed in claim 15 in which the concentration of the alcohol is from 1 to 40% by weight of the aqueous phase.

A composition as claimed in any one of claims 1 to 16 in which the amount of the polymeric surfactant is of from 0.5 to 5% by weight of the total emulsion. A composition as claimed in any one of claims 1 to 17 in which the oil phase is an emollient oil.

A method of making a multiple water-in-oil-in-water emulsion as claimed in claim 14 which comprises by dispersing a hydrophile-in-oil emulsion as claimed in either claim 12 or claim 13 in water

A method of making an oil-in-water emulsion containing water-in-oil droplets which includes forming a mixture of an oil phase and oil-in-water primary emulsifier for dispersing oil in an aqueous phase including also an oil soluble copolymer surfactant of the formula : A - B - A as defined in any one of claims 1 to 6, and adding to the oil mixture under stirring to an aqueous phase.

A method as claimed in claim 20 in which the primary emulsifier is a combination of a hydrophilic surfactant C₁₂ to C₂₂ fatty alcohol ethoxylate having an average of more than 15 ethoxylate residues per molecule and a hydrophobic surfactant C₁₂ to C₂₂ fatty alcohol ethoxylate having an average of not more than 5 ethoxylate residues per molecule.

A method as claimed in claim 21 in which the relative amounts of hydrophilic surfactant and hydrophobic surfactant are in the weight range 3:1 to 1 :5.

A method as claimed in any one of claims 20 to 22 in which the primary emulsifier additionally includes C₁₂ to C₂₂ fatty alcohol and the weight ratio of fatty alcohol to the combination of the hydrophilic and hydrophobic surfactants is in the range 1 :10 to 1 :1.

A method as claimed in any one of claims 20 to 23 in which the amount of the polymeric surfactant used is from 0.1 to 2% by weight of the total multiple emulsion.

A method as claimed in any one of claims 20 to 24 in which the amount of the primary emulsifier surfactant system (including any additional fatty alcohol) used is from 0.5 to 12% by weight of the total multiple emulsion.