WO1996025137A1 - Multiple w/o/w emulsions - Google Patents

Abstract

Stable multiple W/O/W emulsions are obtained by making a primary W/O emulsion I from an oil and a water phase in the presence of polyol polyhydroxy stearates as emulsifiers and then emulsifying it with an aqueous phase II.

Description

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The invention relates to multiple W / O / W emulsions containing polyol polyhydroxystearates as emulsifiers, a process for their preparation and the use of polyolpolyhydroxystearates as emulsifiers for the production of multiple W / O / W emulsions.

Status of the appointment <* ^•

Multiple emulsions are emulsions of emulsions. Depending on the production, a distinction is made between multiple water / oil / water (W / O / W) and oil / water / oil (0 / W / O) emulsions. The most important application of multiple emulsions is to process active ingredients that are otherwise not miscible or ready for assembly in a recipe. Another advantage is that the active ingredients can be released in a controlled manner over a longer period of time. Multiple emulsions are therefore particularly important for the production of cosmetic and pharmaceutical products [Cosm.Toil. 105, 65 (1990) and 106, 97 (1991)]. A particularly elegant process for the preparation of multiple emulsions is described by S.Matsumoto in J.Coll.Inter .Sei 57.353 (1976): After this, a pre-emulsion is first produced at elevated temperature and with strong shear, which is then introduced into the aqueous solution of a hydrophilic emulsifier at ambient temperature and under low shear. Sorbitan monoleate and polyethylene glycol derivative are used as the emulsifier pair.

It is also known from the extensive prior art that monoglycerides, sorbitan esters, polysorbates and highly ethoxylated fatty alcohols are in principle suitable as hydrophilic emulsifiers for the production of multiple emulsions. Here is representative of the publications in Phaπa. Acta.Helv. 6_, 343 (1991), and by Seiller and Luca in Bull.Tech./Gattefosse Rep. B_, 27 (1987), STP Phar-na 4., 679 (1988) and Int.J.Cosne .Sei. l_ _r 1 (1991).

From Takuga u Zasshi 112, 73 (1992), W / O / W emulsions are also known which contain glycerol trifatty acid esters as oil bodies and hydrophilic polymers, such as gelatin, as stabilizing agents. The use of albumin and polyacrylates as stabilizers for the water phase and nonionic surfactants for the oil phase is known from J. Controlled Release 3, 279 (1986). However, such formulations have proven to be insufficiently stable in storage, in particular in the case of temperature fluctuations. The use of polyglycerol polyricinoleates as emulsifiers for the production of multiple emulsions is also known from European patent application EP-AI 0174377 (Meji Milk Products). Also however, these emulsions have not proven to be sufficiently stable, particularly in the case of temperature fluctuations.

In order to produce stable multiple emulsions, the use of high molecular weight, lipophilic emulsifiers is required. In an essay by P.Hameyer and K.R.Jenni in Parf.Koβ. 75, 12, 842 describes, for example, the use of cetyl dimethicone copolyols. However, because of the proportion of polyoxyethylene groups, this group of emulsifiers for use in skin cosmetic products has been discussed controversially recently. Also from a publication by K. Stickdorn et al. in Parf.Koβm. Processes for the production of multiple emulsions are known. This describes both two-stage processes with hydrophilic, ethylene oxide-containing emulsifiers in the secondary emulsion and single-stage processes using exclusively EO-containing emulsifiers, for which the abovementioned concerns can also apply.

The object of the invention was therefore to provide stable multiple W / O / W emulsions which are also resistant to temperature fluctuations and which, from an application point of view, have a lipophilic emulsifier which is at least equivalent to cetyl dimethicone copolyols, but with contain improved skin cosmetic properties. Furthermore, the emulsions should be as free as possible of hydrophilic, co-emulsifiers containing ethylene oxide. Description of the invention

The invention relates to multiple W / O / W emulsions which are obtained by first preparing a primary W / O emulsion I from an oil phase and a water phase in the presence of polyol polyhydroxystearates as emulsifiers, and then producing this emulsified with a water phase II.

Surprisingly, it has been found that polyol polyhydroxystearates in general and polyglycerol polyhydroxy stearates in particular are suitable as effective lipophilic emulsifiers for the preparation of multiple W / O / W emulsions and thus represent an at least equivalent substitute for cetyl dimethicone copolyols from an application point of view; at the same time, the ethylene oxide-free polyol polyhydroxy stearates have better skin cosmetic properties. The invention also includes the knowledge that the use of hydrophilic ionic or nonionic emulsifiers for stabilizing the phases is no longer absolutely necessary. Finally, the polyglycerol polyhydroxystearates have been shown to be significantly improved over polyglycerol polyricinoleates with regard to the temperature dependence of the emulsifying action.

Polvolpolvhvdroxystearate

The polyol polyhydroxystearates which are suitable as emulsifiers for the production of multiple W / O / W emulsions in the sense of the invention are known substances which are prepared by the relevant methods of preparative organic African chemistry can get. For their preparation, for example, polyhydroxystearic acid with a degree of self-condensation in the range from 2 to 20, preferably 2 to 10, can be esterified with polyols in a manner known per se.

The polyol polyhydroxystearates can be derived from polyols which have at least two, preferably 3 to 12 and in particular 3 to 8 hydroxyl groups and 2 to 12 carbon atoms. Typical examples are glycerol, alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol; Polyglycerin; Methyl compounds, such as in particular trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol and dipentaerythritol; Alkyl glucosides with 1 to 22, preferably 1 to 8 and in particular 1 to 4 carbons in the alkyl radical, such as, for example, methyl and butyl glucoside; Sugar alcohols with 5 to 12 carbon atoms such as, for example, sorbitol or mannitol, sugars with 5 to 12 carbon atoms such as, for example, glucose or sucrose; or aminosugars such as glucamine.

In a preferred embodiment, the emulsifiers used are polyglycerol polyhydroxystearates which are obtained by polyhydroxystearic acid having a degree of self-condensation in the range from 2 to 20, preferably 2 to 10, with a polyglycerol mixture of the composition (GC method)

Glycerin 5 to 35 (15 to 30) wt% diglycerols 15 to 40 (20 to 32) wt% triglycerols 10 to 35 (15 to 25) wt% tetraglycerols 5 to 20 (8 to 15) wt. % Pentaglycerols 2 to 10 (3 to 8)% by weight (Oligoglycerols ad 100 wt .-%) esterified in a conventional manner; the preferred areas are given in brackets.

The polyol polyhydroxystearates can be prepared in a manner known per se. In the case of the polyglycerol polyhydroxystearates, the polyglycerol is preferably first produced and then the polyhydroxystearic acid, and finally both are esterified.

A polyglycerol of the abovementioned composition can be prepared by self-condensation of glycerol in the presence of suitable catalysts such as, for example, potassium carbonate, silicates according to DE-Al 4029323 (Henkel) or borates according to DE-Al 4117033 (Henkel) at temperatures in the range of 200 to 260 ° C are carried out.

The polyhydroxystearic acid is prepared, for example, by alkaline-catalyzed polycondensation of hydroxystearic acid, preferably 12-hydroxystearic acid, which is obtained by curing ricinoleic acid or technical castor oil fatty acid. Linear esterification products having 2 to 10 and in particular 2 to 8 fatty acid units are preferably formed. The following distribution (GPC method) is typically achieved:

Monomers 1 to 10% by weight

Dine 5 to 15% by weight

Trimers 5 to 15% by weight

Tetramers 5 to 15% by weight

Pentamers 5 to 15% by weight Hexamers: 5 to 15% by weight

Heptamers: 5 to 15% by weight

Octamers: 1 to 10% by weight

Oligomers: ad 100% by weight

In a particular embodiment of the invention, mixtures of hydroxystearic acid and ricinoleic acid or technical castor oil fatty acid, which consists of approximately 90% by weight of ricinoleic acid, in a weight ratio of 90:10 to 50:50 and preferably 75:25 to 60: 40 used. In the same way, it is possible to condense the acids individually and then to mix the condensates.

In the subsequent condensation of the polyol component, for example the polyglycerol with the polyhydroxystearic acid or the mixtures with polyricinoleic acid, a complex mixture of homologous polyesters is formed. The proportions of mono-, di-, tri- and oligoesters in the polyol polyhydroxystearates according to the invention and preferably polyglycerol polyhydroxy stearates depend on the conditions of use of the starting compounds. In a preferred embodiment of the invention, an emulsifier with particularly advantageous performance properties is used, which is obtained by subjecting about 1000 kg of 12-hydroxystearic acid to self-condensation until a product with an acid number in the range from 50 to 55 results and this is then further esterified with about 150 kg of polyglycerol of the composition given above until the acid number has decreased to a value of less than 2. oil phase A

In addition to oil bodies and co-emulsifiers, the oil phase can also contain fats, waxes, stabilizers and superfatting agents.

Guerbet alcohols based on fatty alcohols with 6 to 18, preferably 8 to 10 carbon toners, esters of linear C -C20 fatty acids with linear C6-C20 ^{fats oil} / h ° l ^βn / esters of branched Cβ come as oil bodies, for example -Ci3- carboxylic acids with linear Cß-Ci8- ^fatty acids, esters of linear Cg-C ^ g fatty acids with branched alcohols, in particular 2-ethylhexanol, esters of linear and / or branched fatty acids with polyhydric alcohols and / or Guerbet alcohols, triglycerides based on C5-Cιo ~ ^{Fe <t t} acids, vegetable oils, branched primary alcohols, substituted cyclohexanes, Guerbet carbonates and / or dialkyl ethers into consideration.

Both known W / O and O / W emulsifiers such as, for example, polyglycerol fatty acid esters or glycerol fatty acid esters can be used as co-emulsifiers.

Typical examples of fats are glycerides, waxes, etc. Beeswax, paraffin wax or micro waxes optionally in combination with hydrophilic waxes, e.g. Cetyl stearyl alcohol in question.

Metal salts of fatty acids such as magnesium, aluminum and / or zinc stearate can be used as stabilizers. Substances such as, for example, polyethoxylated lanolin derivatives, lecithin derivatives, polyol fatty acid esters, monoglycerides and fatty acid alkanolamides can be used as superfatting agents, the latter optionally serving at the same time as foam stabilizers.

Water phase B or II

The water phase B, which is processed with the oil phase A to form the primary W / O emulsion I, can, in addition to water - the main constituent of which is approximately 50 to 85% by weight, based on the primary W / O emulsion - also polyols such as preferably contain glycerol and electrolyte salts such as table salt, ammonium chloride or magnesium sulfate.

The water phase II, which results in the multiple W / O / W emulsion with the primary W / O emulsion I, can in principle have the same ingredients. In addition to the main constituent water, which in turn usually makes up 50 to 85% by weight, based on the multiple W / O / W emulsion, it may in particular contain polymers or thickening agents. Typical examples of this are polysaccharides, in particular xanthan gum, guar guar, agar agar, alginates and tyloses, carboxymethyl cellulose and hydroxyethyl cellulose, furthermore higher molecular weight polyethylene glycol mono- and diesters of fatty acids, polyacrylates, polyvinyl alcohol and polyvinyl pyrrolidone.

Finally, preservatives such as, for example, phenoxyethanol, formaldehyde solution, parabens, pentanediol or sorbic acid can also be present. Preparation of the multiple emulsions

Another object of the invention is a process for producing multiple W / O / W emulsions, in which a primary W / O emulsion I is prepared from an oil and a water phase in the presence of polyol polyhydroxy stearates as emulsifiers, and this then emulsified with a water phase II.

To produce the primary W / O emulsion, the oil phase is preferably heated to temperatures in the range from 50 to 90 ° C. together with the emulsifier - that is to say the polyol polyhydroxystearate and preferably the polyglycerol polyhydroxy stearate - and then the likewise preheated water phase is stirred in . The emulsifiers are preferably used in amounts of 1 to 10 and in particular 2 to 4% by weight, based on the primary W / O emulsion I. The weight ratio between oil phase A and water phase B can be in the range from 50:50 to 10:90 and preferably 30:70 to 40:60.

After the primary W / O emulsion has been prepared, it is preferably reacted at room temperature with vigorous stirring with the water phase II to form a multiple W / O / W emulsion, the weight ratio of the two components W / O emulsion to water phase II 15: 85 to 70:30 and preferably 30:70 to 60:40 may be. In conclusion, it may be advantageous to adjust the multiple emulsion to a skin pH in the range from 5 to 6 by adding, for example, alkali metal hydroxide. In principle, the emulsions can also be produced by cold, hot, hot-hot / cold or PIT emulsification. This is a purely mechanical process, there is no chemical reaction.

Industrial applicability

The multiple W / O / W emulsions according to the invention are notable for particular stability, in particular even at fluctuating temperatures. Another object of the invention therefore relates to the use of polyol polyhydroxystearates in general and polyglycerol polyhydroxy stearates in particular as emulsifiers for the preparation of multiple W / O / W emulsions in which they are used in amounts of 0.1 to 10, preferably 0, 2 to 4% by weight, based on the multiple emulsions, can be present.

The multiple W / O / W emulsions in turn can be used to produce cosmetic and pharmaceutical preparations such as creams, ointments and lotions.

The following examples are intended to explain the subject matter of the invention in more detail without restricting it. example

Preparation of the primary W / O emulsion. An oil phase A consists of

6.0% by weight of dicapryl ether (Cetiol ( ^R ) OE),

6.0% by weight hexyl laurate (Cetiol ( ^R ) A),

7.0% by weight of cetearyl isononanoate (Cetiol ( ^R ) SN),

3.0% by weight of isocetyl alcohol (Eutanol ( ^R ) G 16),

1.0% by weight of glyceryl oleate (Monomuls ( ^R ) 90-O 18),

1.0% by weight beeswax and

1.0% by weight of zinc stearate and

3 wt .-% of the emulsifier Polyglyceryl-2-polyhydroxystearate (Dehymuls ^(R) PGPH) were stirred at 80 C ^β melted and homogeneous. In addition, a water phase B consisting of 66.0% by weight of water, 5.0% by weight of glycerol and 1.0 magnesium sulfate was also heated to 80 ° C., added slowly to the oil phase A and stirred for 5 minutes 80 ° C emulsified. The resulting primary W / O emulsion I was cooled and homogenized at 60 ° C. The stirring was ended after 30 min (percentages based on W / O emulsion).

Preparation of the multiple W / O / W emulsion. 60% by weight of a water phase II consisting of 99.4% by weight of water, 0.3% by weight of Carbopol ( ^R ) 981 and. Was slowly added to 40% by weight of the primary W / O emulsion I while stirring Given 0.2 wt .-% formaldehyde. The pH was then adjusted to 6.5 by adding 0.1% by weight of potassium hydroxide.

Claims

claims 1. Multiple W / O / W emulsions, obtainable by producing a primary W / O emulsion I from an oil and a water phase in the presence of polyol polyhydroxystearates as emulsifiers and then emulsifying them with a water phase II. 2. Multiple W / O / W emulsions according to Claim 1, characterized in that they contain polyglycerol polyhydroxystearates as emulsifiers. 3. Multiple W / O / W emulsions according to claims 1 and 2, characterized in that they contain oil bodies, co-emulsifiers, fats, waxes, stabilizers and / or superfatting agents as the oil phase. 4. Process for the preparation of multiple W / O / W emulsions, in which a primary W / O emulsion I is prepared from an oil and a water phase in the presence of polyol polyhydroxystearates as emulsifiers, and this is then combined with a water phase II emulsified. 5. The method according to claim 4, characterized in that the emulsifiers in amounts of 1 to 10 wt .-% - based on the primary W / O emulsion I - used. 6. The method according to claims 4 and 5, characterized gekenn¬ characterized in that the oil phase A and the water phase B in a weight ratio of 50:50 to 10:90 is used. 1 7. Process according to Claims 4 to 6, characterized in that the primary W / O emulsion and the water phase II are used in a weight ratio of 15:85 to 70:30. 8. Use of polyol polyhydroxystearates as emulsifiers for the production of multiple W / O / W emulsions.