COSMETIC CLEANSING COMPOSITIONS COMPRISING ESTERS OF ALKYLGLYCOSIDES

Abstract: A cosmetic cleansing composition in a water-soluble capsule (preferably gelatin) comprises: (a) 30-85 wt.% (preferably 60-85 %) of C10-C22 fatty acid ester of C1-C4 alkylglycoside (preferably having at least 50 wt.% of mono-ester); (b) 10-20 wt.% alkali metal salt of C10-C20 alkyl sulphate; (c) 1-30 wt.% of an alkoxylated sorbitan C10-C22 fatty acid ester (preferably polyoxyethylene (20) sorbitan monolaurate); (d) 0-30 wt.% of C10-C22 fatty acid dialkylolamide (preferably coconut fatty acid diethanolamide) and at most 4 wt.% (preferably at most 3 wt.%) of water, the composition having a viscosity of 6,500-15,000, preferably 7,000-12,000 mPas (at 20 DEG C). Effective amounts of functional additives may also be present.

Description: COSMETIC CLEANSING COMPOSITIONS COMPRISING ESTERS OF ALKYLGLYCOSIDES The present invention relates to a cosmetic cleansing composition in a water-soluble capsule. Traditional cosmetic cleansing compositions, like hair and body shampoos, shower products and foam bath preparations are based on sodium alkyl sulphate, and even more on sodium alkyl ether sulphates. In order to stabilise and boost foam and also for reasons of skin mildness often coconut diethanolamide is added, but this leads to a rather uncontrolled increase in viscosity and it tends to darken the colour of the solutions. Sometimes betaines are used to further reduce skin irritation and to effect a viscosity synergism between the anionic sodium lauryl ether sulphate and the amphoteric oleyl betaine to yield very viscous (gel) products. It has been proposed in United States Patent Specification US-A-3, 705, 102 (Armour-Dial Inc.) to provide a bath composition with a high-foaming detergent and an encapsulated combination of an emollient, a fatty polyoxyethylene material (HLB=10-12) and a methyl- polysiloxane defoaming agent. In use, the detergent provides copious foam and, after a delay in time, the encapsulated materials are released to simultaneously break the foam produced by the detergent and provide an emollient for the skin of the user. The disadvantage of this method is that the capsule may release its content too early and also that the emollient is not available throughout the entire cleansing process. The presence of such an emollient yields a sensation of mildness to the skin. It is therefore proposed to encapsulate the entire cosmetic cleansing composition in a water-soluble capsule, which is preferably made of gelatin. The problem is here that most high-foaming detergents, like the alkali metal salts and the amine salts of the high-foaming alkyl sulphates - such as e.g. triethanolamine lauryl sulphate - always contain an appreciable amount of water. The presence of this relatively large amount of water leads to an undue softening and even rupture of the gelatin capsule, thus untimely releasing its contents. Another problem is that during the manufacture of the capsules the cosmetic cleansing composition should have a relatively high viscosity, so as to enable its encapsulation, whereas upon use the composition after breakage of the capsule should quickly dissolve or disperse in the aqueous environment. It has now been found that these problems can be solved by providing a cosmetic cleansing composition in a water- soluble capsule, preferably made of gelatin, which composition comprises an alkali metal salt of an alkyl sulphate, a fatty acid ester of an alkylglycoside having an alkyl group with from 1 to 4 carbon atoms and a sorbitan (or anhydrohexitol) ester of a fatty acid alkoxylated with preferably ethylene oxide, and, optionally a fatty acid dialkylolamide. It has been found that the viscosity of the product was dependent on the shear exerted upon it. For example 1 it was found that at very low shear (below to 10 sec "1 ) the viscosity of the product was 8,000 mPas; then with increasing shear (to 50 sec "1 ) the viscosity increased to 8,300 mPas and at constant shear of 50 sec "1 the viscosity increased further to 9,100 mPas. If the shear was then decreased, the viscosity further increased to 15,000 mPas. After some time, the viscosity started to decrease again. It may therefore be stated that the product is both shear thickening or dilatant and exhibits rheopexy. This rheological behaviour is of advantage during finishing and in using the product. During finishing of this type of products a relatively high viscosity is required (in the order of 8,000 to 12,000 mPas) . If the product after finishing is left to rest, its viscosity will decrease to its original value at low shear, so that upon use the product will easily dissolve or disperse in water. Moreover it was surprising to note that the mildness to the skin of the final formulation was comparable to the mildness of the pure fatty acid ester of C1-C4 alkylglycoside, notwithstanding the still appreciable level of the alkali metal salt of alkyl sulphate, known to be a skin irritant. Therefore, the present invention relates to a cosmetic cleansing composition in a water-soluble capsule, which composition comprises: (a) from 30 to 85% by weight of an ester of an alkylglycoside having an alkyl group with from 1 to 4 carbon atoms and a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms; (b) from 10 to 20% by weight of an alkali metal salt of an alkyl sulphate, having from 10 to 20 carbon atoms; (c) from 1 to 30% by weight of a sorbitan ester of a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms, alkoxylated with from 10 to 80 moles of a C1-C4 alkylene oxide; (d) from 0 to 30% by weight of a straight or branched chain, saturated or unsaturated C10-C22, fatty acid dialkylol amide, and (e) at most 4% by weight of water, said composition having a viscosity from 6500 to 15000 mPas. The fatty acid ester of the alkylglycoside having an alkyl group with from 1 to 4 carbon atoms preferably is a fatty acid ester of methyl glucoside, methyl fructoside, ethyl glycoside or ethyl fructoside. The fatty acid may be a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms. The use of lauric acid, palmitic acid, stearic acid and iso-stearic acid is preferred. Also fatty acid mixtures may be used, such as coconut fatty acids, palm kernel fatty acids and tallow fatty acids. The use of coconut fatty acids, of which the fatty acids up to and including octanoic acid have mainly been removed, is preferred. Generally, the fatty acid esters of the alkylglycosides comprise mono-, di-, tri- and higher esters. The use of esters comprising at least 50% by weight, preferably at least 75% by weight, of mono esters is preferred. The esters may comprise up to 15% by weight of free fatty acids, but preferably the free fatty acid content is as low as possible, e.g.below 3% by weight. Generally from 30 to 85% by weight of alkylglycoside ester is used, preferably from 60% to 85% by weight, and most preferably from 70% to 80% by weight. The alkali metal salt of the alkyl sulphate preferably is the sodium salt. The alkyl sulphate contains from 10 to 20 carbon atoms, such as dodecyl, lauryl, hexadecyl, myristyl and octadecyl sulphate. The use of lauryl sulphate is preferred. In general amine salts or alkanolamine salts are not used in view of the possibility of skin irritation. Generally from 10% to 20% by weight of the alkali metal salt of C 10 - C 20 alkyl sulphate is used. The alkoxylated sorbitan fatty acid esters are derived from sorbitan (or anhydrohexitol) . The fatty acids may be straight or branched chain, saturated or unsaturated fatty acids having from 10 to 22 carbon atoms, such as lauric acid, stearic acid, palmitic acid, oleic acid, iso-stearic acid and the like. The sorbitan fatty acid esters have been alkoxylated with C1-C4 alkylene oxides, preferably ethylene oxide, or mixtures of such alkylene oxides. On an average from 10 to 80 moles of alkylene oxide per mole of sorbitan fatty acid ester are reacted. The use of polyoxyethylene (20) orbitan monolaurate is preferred. The alkoxylated sorbitan fatty acid ester is used in an amount of from 1% to 30% by weight, preferably from 5% to 25% by weight of the total composition. The fatty acid dialkylolamide is derived from a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms, such as lauric acid or coconut acids of which the fatty acids up to and including octanoic acid have mainly been removed. In the latter case the term "coconut fatty acid dialkylolamide" is used and these dialkylolamides are preferred. The hydroxyalkyl groups of the dialkylolamide have from 2 to 5 carbon atoms and these groups may the same or different and may be mono- or polyhydroxyalkyl. The use of coconut fatty acid diethanolamide is preferred. The fatty acid dialkylolamide is used in an amount of up to 30% by weight of the total composition, preferably from 15% to 25% by weight. Since the presence of water up to a certain level may lead to undue rupture of the gelatin capsules, the amount of water in the cosmetic cleansing composition is at most 4% by weight and preferably at most 3% by weight. The cosmetic cleansing compositions according to the present invention may also comprise an effective amount (in general up to 10% by weight, but greater amounts may be used) of a functional additive, selected from the group consisting of perfumes, chelating or sequestering agents (like EDTA) , preservatives, bactericides, herbs (or herb extracts) , vitamins, buffering substances, moisturizers, emollients (such as esters of fatty acids and/or fatty alcohols) , viscosity controlling agents (such as monohydric alcohols with 2 to 8 carbon atoms) , anti-oxidants, dyes, lather boosters (such as higher alkyl amine oxides) , and mixtures thereof . The viscosity of the cosmetic cleansing composition as measured with a rotation viscosimeter at 20°C using spindle No SV1 is from 6,500 to 15,000 mPas, preferably from 7,000 to 12,000 mPas. The water-soluble capsule material is preferably gelatin, but other material like polyvinyl alcohol may be used. The release time of the capsule may be controlled by the selection of the wall thickness of the capsule and the type of gelatin (different Bloom strength) . The capsule may have a well thickness of 0.1 mm to 1 mm and a volume of for example 5 ml . It is known from Seifen-Oele-Fette- achse, Vol. 117, No. 4, 124-131 (1991) , particularly pages 128 and 129, that methyl glucoside laurate and methyl glucoside iso-stearate exhibit excellent thickening properties, when used in combination with an aqueous solution of 12% by weight of sodium lauryl ether sulphate. There is a marked difference, however, between sodium lauryl sulphate and sodium lauryl ether sulphate and no predictions can be made, that if a certain substance has a thickening effect on an aqueous sodium lauryl ether sulphate solution, it will have the same effect on almost water-free sodium lauryl sulphate. Moreover, it is clear from Figures 9 and 10 on page 129 that in the absence of salt there is apparently no thickening effect. The present invention therefore cannot be derived from this publication. The invention will now be illustrated on hand of the following examples. Example 1 A cosmetic cleansing composition was prepared by mixing the following ingredients (in % by weight) Lauric acid ester of ethyl glucoside 67.0 % Sodium Lauryl sulphate 12.0 % Polysorbate-20 10.0 % Ethanol (96%) 5.0 % Ethylene diamine tetra-acetic acid (40 wt% aqueous solution) 4.0 Water 0.6 % Perfume 0.1 % Emollient 0.55% Citric acid (60 wt% aqueous solution) 0,75% 100.0 The lauric acid ester of ethyl glucoside contained 65.5% by weight of mono-ester, 14.8% by weight of di-ester, 19.1% by weight of tri-ester and 0.6% by weight of higher ester. Polysorbate-20 (Trade Mark; ex. Atlas Chem.) is poly- oxyethylene (20) sorbitan monolaurate in which on an average 20 moles of ethylene oxide are present, having a HLB value of 16.7 and a viscosity at 25°C of 330 cSt (mm 2 S "1 ) . After mixing a transparent liquid was obtained, which in a 1% by weight solution in water has a pH value of 5.7 and has a viscosity of 8,000 mPas (measured with rotation viscosimeter, using spindle no. SV 1 at 20°C) . It was an extremely mild to the skin, copiously foaming cosmetic cleansing composition. Rheological behaviour: at shear below 10 sec "1 viscosity was 8000 mPas; at increasing shear (up to 50 sec "1 ) viscosity increased to 8,300 mPas. At constant shear (50 sec "1 ) for 3 minutes, viscosity increased to 9,100 mPas. At decrease of shear the viscosity increased to 15,000 mPas in 3 minutes. Sheets of gelatin were made and passed through a capsule making machine in a manner known per se, producing capsules having a wall thickness of 0.2-0.7 mm and a volume of 5 ml, which were filled with the above prepared cosmetic cleansing composition. Examples 2 and 3 Example 1 was repeated, now using the following formulations (ingredients in % by weight of the total composition) : Example 2 Example 3 Lauric acid ester of ethyl glucoside (as in Example 1) 39 % 40 % Lauric acid 4 % - Sodium lauryl sulphate 12 % 12 Coconut fatty acid diethanolamide 20 % 20 o, o Polysorbate-20 (as in Example 1) 20 % 20 % Ethanol (96%) 1 % 4 % Perfume 0.10% 0.10% Emollient 0.55% 0.55% Water 3,35% 3,35% 100.00% 100.00% In both examples the gelatin capsules filled with the formulations as described in Example 1, upon use yielded a copiously foaming, mild to the skin cosmetic cleansing composition.

Claims: CLAIMS 1. A cosmetic cleansing composition in a water-soluble capsule, said composition comprising: (a) from 30 to 85% by weight of an ester of an alkylglycoside having an alkyl group with from 1 to 4 carbon atoms and a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms : (b) from 10 to 20% by weight of an alkali metal salt of an alkyl sulphate having from 10 to 20 carbon atoms; (c) from 1 to 30% by weight of a sorbitan ester of a straight or branched chain, saturated or unsaturated fatty acid having from 10 to 22 carbon atoms, alkoxylated with from 10 to 80 moles of a C1-C4 alkylene oxide; (d) from 0 to 30% by weight of a straight or branched chain, saturated or unsaturated C10-C22, fatty acid dialkylol amide, and (c) at most 4% by weight water, said composition having a viscosity from 6500 to 15,000 mPas. 2. A cosmetic cleansing composition according to claim 1, in which (a) is a C 10 -C 22 fatty acid ester of an alkylglucoside having an alkyl group with 1 or 2 carbon atoms. 3. A cosmetic cleansing composition according to claim 1, in which (a) comprises at least 50% by weight of mono- ester. 4. A cosmetic cleansing composition according to Claim 1. in which (a) comprises at least 75% to weight of mono- ester. 5. A cosmetic cleansing composition, according to Claim 1, in which (a) comprises at most 3% by weight of free fatty acids . 6. A cosmetic cleansing composition according to claim 1, in which in (a) the fatty acid is selected from the group consisting of lauric acid, palmitic acid, stearic acid, iso-stearic acid and coconut fatty acids of which the fatty acids up to and including octanoic acid have been removed. 7. A cosmetic cleansing composition according to Claim 1, in which from 60% to 85% by weight of the total composition of (a) is used. 8. A cosmetic cleansing composition according to claim 1, in which (b) is sodium lauryl sulphate. 9. A cosmetic cleansing composition according to Claim 1, in which in (b) the alkylene oxide is ethylene oxide. 10. A cosmetic cleansing composition according to Claim 1, in which (b) is polyoxyethylene (20) sorbitan monolaurate. 11. A cosmetic cleansing composition according to Claim 1, comprising from 5% to 25% by weight of the total composition of (b) . 12. A cosmetic cleansing composition according to Claim 1, in which (d) is coconut fatty acid diethanolamide. 13. A cosmetic cleansing composition according to Claim, comprising from 15% to 25% by weight of the total composition of (d) . 14. A cosmetic cleansing composition according to claim 1, which comprises at most 3% by weight of water. 15. A cosmetic cleansing composition according to claim 1, which comprises up to 10% by weight of the total composition of a functional additive selected from the group consisting of perfumes, chelating agents, preservatives, bactericides, herbs, vitamins, buffering substances, moisturizers, emollients, viscosity controlling agents, antioxidants, dyes, lather boosters, and mixtures thereof. 16. A cosmetic cleansing composition according to claim 1, having a viscosity of 6,500 to 15,000 mPas (at 20°C) . 17. A cosmetic cleansing composition according to Claim 1, having a viscosity of 7,000 to 12,000 mPas (at 20°C) . 18. A cosmetic cleansing composition according to claim 1, in which the capsule material is gelatin. 19. A foam bath preparation comprising a cosmetic cleansing composition according to Claims 1 - 18.

Inventors: OOSTERMAN JACOB, PETERS DE BOER HELEEN, OOSTERMAN, JACOB, PETERS DE BOER, HELEEN
Applicants: OOSTERMAN JACOB, PETERS DE BOER HELEEN, UNICHEMA CHEMIE BV, OOSTERMAN, JACOB, PETERS DE BOER, HELEEN, UNICHEMA CHEMIE B.V.
Application year: 1996
Main classification: A61K7
IPC codes: A61K8, A61Q19, C11D1, C11D17