CA2105873A1

CA2105873A1 - A topical soap gel preparation

Info

Publication number: CA2105873A1
Application number: CA002105873A
Authority: CA
Inventors: Bernhard Banowski; Claudia Meyer
Original assignee: Individual
Current assignee: Henkel AG and Co KGaA
Priority date: 1991-03-09
Filing date: 1992-03-02
Publication date: 1992-09-17
Also published as: FI933892A0; WO1992015280A1; DE4107712A1; HUT65716A; JPH06505245A; EP0575373A1; HU9302548D0; FI933892A

Abstract

Disclosed is a soap-gel preparation for the topical application of cosmetic and pharmaceutical substances, in particular a preparation in the form of a stick, the preparation being based on a soap gel consisting of 3-10 % by wt. of alkali soaps of a C16-C22 fatty-acid mixture, 30-90 % by wt. of polyols and 1-30 % by wt.
of water. Preparations of this kind are particularly transparent, are dimensionally stable and have satisfactory release characteristics on contact with the skin when the fatty-acid mixture contains 60-95 % by wt. of saturated straight-chain fatty acids and 5-40 % by wt. of saturated branched-chain fatty acids.

Description

Wo 92/15280 2 1 0 ~ ~ 7 3 PCT/EP92/qO~56 A topiaal ~o~p gel pr~paratio~

This invention relates to a shaped preparation based on a soap gel for the application of active cosmetic and pharmaceutical substances, particularly in stick form, which, by virtue of its composition, shows very good dimensional stability at normal temperature coupled with good trans~er properties and which is substantially free from lower alcohols.
Soap gels as carriers ~or topical cosmetic and pharmaceutical active substances h~ve long been known.
Sodium stearate gels in aqueous lower alcohols and glycols are normally used as the soaps. Unfortunately, gels such as these have the disadvantage that they are generally too stiff and, when applied to the skin, only transfer very little product thereto. In order to improve the transfer properties of soap gel preparations Q~ the type in question, it was proposed in US 2,900,306 to incorporake a water-soluble myristic a~id soap in the preparation. Other documents recommended the addition of fatty acid esters and ethylene oxide and propylene oxi~e condensates to improve ~he gel time and to reduce, syneresis and;tackine s (U8 4,617~1~5). Some of these additives have an unfavorable ~ffect on the transparency of the preparation.
Accordingly, the problem addressed by the present invention was to provide a~shaped soap gel preparation ~` which ~would~ show high transparency, high dimensional stability and satisfactory trans~er on contact with ~he skin. ~ ~
~ According to the invention, this problem has been . .
sol~ed by a soap gel preparation~for the topical appli-cation of cosmetic and pharmaceutical substances based on a gel of alkali metal soaps containing :: :

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2105~73 wo 92/15280 2 ~cT/Eps2/oo4s6 3 to 10% by weight of a mixture of Cl622 fatty acids in the form of their alkali metal soaps, 30 to 90% by weight polyols containing 3 to 6 carbon atoms and 2 to 6 hydro~yl groups, 1 to 30% by weight water and active cosmetic or pharmaceutical substances and, optionally, other typical auxiliaries, characterized in that the fatty acid mixture contains 60 to 95% by weight linear saturated fatty acids and 5 to 40% by weight branched ~akurated fatty acids.

The effect o~ the presence of soaps of branched-chain fatty acids is that, although the preparations ; retain their firmness at temperatures below 35C, they :~ immediately melt to a limited extent and become slippery on contact with the skin SG that a thin film of the prepar~tion can easily b~ applied to the skin.
Suitable linear saturated fatty acids are pal-mitic acid,~stearic acid, arachic acid and behenic acid ~: ; or technical mixtures predominantly consisting of such ~ ~ : fatty acids, for e~ample hydrogenated palm oil fatty :~ 25 acid or hydrogenated tallow fatty acid~ Stearic acid is preferably used.~ ~
` Suitable branched saturated fatty acids are, for example, 2-hexyl decano:ic acid, 2-octyl dodecanoic acid or~other branched fatty acids containing 16 to 22 carbon ;: 30 atoms. ; ;~
` ~ However,~ :isostearic acid is particularly suit-able. Isostea~ric a~id is mainly understood to be a mixture of l~iquid,~ branched-~chain isomers of stearic a~id~which~ may be obtain~ed by hydrogenation of the `~ 35 ~isomexic liquid monomer fatty acids formed as secondary :~ ;

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2~L0~73 Wo 92/15280 3 PCT/EP92/OQ456 product in the dimerization of unsaturated fatty acids.
This isostearic acid and other branched ~atty acids are described in detail in J. ~m. Qil~ Chem. ~QC. November lg79 (Vol. 56), pages ~23A - ~27A~ Accordingly, the branched fatty acid in question is a mixture of which the principal constituents are methyl-branched isomers.
Isostearic acid is a commercial product and is marketed, for example, under the n~me ~mersol 875 ~Henkel Corp.~.
The mixture of linear and branched fatty acids is completely or predominantly present in ~he form of an alkali metal salt (alkali metal soap), preferably in the form of sodium soap. However, a cerkain percentage content o~ free unsaponi~ied fatty acid, for example of the order of 0~01 to 0.5% by weight, based on the preparation as a whole, is not problematical.
The quantity ratio o~ linear to branched fatty acids in the fatty acid mixtuL~e to be used in accordance with the invention has a bearing on the firmness of the soap gel preparation and on its transfer behavior.
Firmness decreases and transfer to the skin increases , with increasing isostearic acid content. However, these parameters are also inf1uenced by the total content of fatty acids ~in the gel. ~The ~atty acid mixture is preferably;used in a ~uantity of 5 to ~ by weiyht. The -~ 25 fatty acid mixture preerably consists of 80 to 95% by weight stearic acid ~and 5 to 20% by weight branched saturated fatty acids. ~ ~
Suitable pol~yols containing 3 ~o 6 carbon atoms and 2 to 6~hydroxyl groups~;are, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,!l,2-I' / . ,~ ' I / , ': ~ ~
butylene glycol, 1,3-butylene glycol, 1,4-butylene gly-col~, glycerol, erythritol,~pentaerythritol, trimethylol propane, sorbitol, anhydrosorbitol, cyclohexane triol, inositol. Propyle~e glycols and glycerol individually or in admixture with sorbitol and/or butylene glycol are ::

wo g2,l5280 2 1 0 ~ 8 7 3 PCT/EP92/00456 particularly preferred. These polyols are preferably present in a total quantity of 70 to 90% by weight, based on the soap gel preparation as a whole. Particu-larly favorable performance properties are obtained when mixtures of 10 to 80~ by weight glycerol, 10 to 80% by weight propylene ylycol and 5 to 20% by weight sorbitol and/or 1,4~butylene glycol are present as the polyols.
A particularly dimensionally stab.le, transparent soap gel preparation showing ~avorable trans~er proper-ties to the skin contains:

5 to 8% by weigh~ of the fatty acid mixture in the form of the sodium so~ps, 70 to 90% by weight polyols from the group con-sisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol or mixtures thereo~ with sorbitol and/or 1,4-butylene glycol and 20 5 to 25~ by weight water.

The soap: gel preparations according to the invention ar~ used for the topical application of active : cosmetic and~pharmaceutical substances. The substances 2S in question are:incorporated în the soap gel prepara~ion in the dosage required:fvr the particular application.
Active casmeti~c substances in the context of the inven-tion are, for example, antimicrobial, deodorizing, skin-moisturizin~ perspiration-inhibiting, depilating, ~: 30 coloring; and~ perfuming substances and also cosmetlc oils. Active~pha~maceutical substances in the context of the invention:are~,~for example, antibiotics, cortico-~ ,. .
steroids:, local~anaesthetics and other substances which may be used against skin disorders. The quantity in ~, ~
~ 35 which the cosmetic or: pharmaceutical substances are ~ ~ :

210~373 Wo 92/15280 5 PCT/EP92/l00456 incorporated is generally of the order of 0.1 to 5% by weight and preferably in the range from 0.1 to 1% by weight, based on the preparation as a whole.
In a particularly preferred embodiment, the soap gel preparations according to the invention are used as stick deodorants. According to the invention, deodoriz-ing substances are present as active cosmetic substances in products such as theæe. Suitable deadorizing sub-stances are, for example, antimicrobial agents such as, for example, 2,4,4'-trichloro-2'-hydroxydiphenyl ether (Irgasan ~P300), chlorhexldine diglucona~e or phenoxy-ethanol, deodorizing antimicrobial ethereal oils, farnesol, lipase inhibitors such as, for example, triethyl citrate or triacetin, astringent substances such as, for example, sodium aluminium chlorohydroxylac-tate and o~her known persunal deodorants or antiper-spirants.
In addition to~the active substances mentioned, the soap gel preparations according to the invention may contain other auxiliaries to improve their appearance and stability in storage. The auxiliarîes in question are, for example, complexing agents, antioxidants, preservatives; fragrances, colorants, opacifiers"
pearlescing pigments;or fine-particle pyrogenic silica.
It has also been found that clouding and crysta~lization in storage can be prevented by adding a water-soluble salt, preferably sodium chloride, in a quantity of approx. O.l;~to 0.3% by weight, based on the soap gel preparation, as a further auxiliary. The total quantity of auxiliaries should~make up no more than 5% by weight ` ' of the soaip gel preparation as a whole, the auxiliaries n question preferably heing present in the preparation in a total quantity of approximately 1 to 3% by weight.
The soap gel prepara~ions according to the invention are preferably free from lower alcohols.

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wo g2/l5280 6 PCT/EPg2~00456 However, up to 10% by weight lower alcohols, for exampleethanol or isoprapanol, may optionally be incorporated in the preparations.
The soap gel preparations according to the invention are best produced by mixing polyols, water and ~atty acid mixtures in a vessel while heating to approx.
50 to ~0C, adding the alkali metal hydroxide to the resulting mixture in the form of a concentrated aqueous solution and stirring until saponification of the fatty acids tQ form a clear solution is complete. The acti~e subskances and auxiliaries may then be successively incorporated during cooling. Finally, the product is poured into a mold, for example into a stick tube, at a temperature above its gel forming temperature and is left to cool therein to a temperature at which it solidifies into a dimensionally stable gel.
The invention is illustrated by the following Examples:

E x a m p 1 e ~

: Soap gel preparations having the composition shown in Table I were prepared as follows:
Polyols, water and fatty acids were mixed in a : 25 vessel and heated to 70~C~ ~ The sodium hydroXide was : added in portions to the resulting mix~ure, the paste becoming clear and homogeneous through saponification.
- After the other additives and the perfume oil had been added, the paste~was poured into stick tubes and left to cool to +20C.
'oap gel sticks com~ining good dimensional : ~ stability with very favorable transfer properties were obtained.

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Claims

1. A soap gel preparation for the topical application of active cosmetic and pharmaceutical substances, more particularly in stick form, based on a gel of alkali metal soaps and containing 3 to 10% by weight of a mixture of C16-22 fatty acids in the form of their alkali metal soaps, 30 to 90% by weight polyols containing 3 to 6 carbon atoms and 2 to 6 hydroxyl groups, 1 to 30% by weight water, 0 to 10% by weight ethanol or isopropanol and active cosmetic or pharmaceutical substances and, optionally, other typical auxiliaries, characterized in that the fatty acid mixture contains 60 to 95%, by weight linear saturated fatty acids and 5 to 40% by weight branched saturated fatty acids.

2. A soap gel preparation as claimed in claim l, characterized in that the linear saturated fatty acid is stearic acid and the branched saturated fatty acid is isostearic acid.

3. A soap gel preparation as claimed in claim 1 or 2, characterized in that propylene glycol and glycerol individually or in admixture with sorbitol and/or butylene glycol are present as polyols in a total quantity of 70 to 90% by weight, based on the preparation as a whole.

4. A soap gel preparation as claimed in claims 1 to 3, characterized in that mixtures of 10 to 80% by weight glycerol, 10 to 80% by weight propylene glycol and 5 to 20% by weight sorbitol and/or 1,4-butylene glycol are present as the polyols.

5. A soap gel preparation as claimed in claims 1 to 4, characterized in that it contains 5 to 8% by weight of the fatty acid mixture in the form of the sodium soaps, 70 to 90% by weight polyols from the group consisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol or mixtures thereof with sorbitol and/or 1,4-butylene glycol and 5 to 25% by weight water.