Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Radical -xh acid – or anhydride – acid halide or salt thereof...
Reexamination Certificate
1999-05-25
2004-03-23
Travers, Russell (Department: 1619)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Radical -xh acid, or anhydride, acid halide or salt thereof...
C514S723000, C514S738000, C424S070280, C424S070310, C424S401000, C510S434000, C554S227000, C554S213000, C554S219000
Reexamination Certificate
active
06710082
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the use of hydroxycarboxylic acid esters obtained by reaction of selected hydroxycarboxylic acids in known manner with selected hydroxyl compounds as thickeners for the production of surface-active formulations.
Surface-active formulations such as, for example, manual dishwashing detergents or hair shampoos, liquid detergents or shower gels are more or less concentrated aqueous surfactant preparations that are all expected to have a viscosity which, on the one hand, is low enough to ensure problem-free handling by the user but which, on the other hand, is also high enough to allow economical use. For preparations which are actually marketed in their in-use concentration and which do not have to be diluted by the user at all before use, this means that the water-thin surfactant solutions have to be adjusted to a relatively high viscosity. In many cases, this is done by the addition of electrolyte salts or polymers. However, in critical cases, including for example anionic surfactants containing internal polar groups and, in particular, sugar surfactants of the alkyl glucoside type, this measure is unsuccessful. Thus, the viscosity of alkyl glucoside solutions, for example, can be distinctly reduced by addition of sodium chloride.
Numerous thickeners with which the viscosity of the “problematical” surfactants mentioned above can be controlled to a greater or lesser extent are known from the prior art. One example of a suitable thickener are the narrow-range fatty alcohol polyglycol ethers known from German patent application DE-A1 3817415 (Henkel). Other suitable thickeners, namely highly ethoxylated glycerol esters, are proposed in German patent application DE-A1 4137317 (Henkel) and in French patent application FR-A 2534923 (Th. Goldschmidt). Esters of citric acid with fatty alcohols are known, for example, from French patent application FR-A 2623422 (L'Oréal). However, it has been found in practice that these thickeners do not produce an adequate or sufficiently stable increase in viscosity so that there is still a need for improved thickeners for the production of surface-active formulations.
Accordingly, the problem addressed by the present invention was to provide thickeners which would even enable aqueous solutions of “problematical” surfactants to be reliably and permanently thickened without adversely affecting the performance properties of the preparations. At the same time, the products would show excellent ecotoxicological compatibility.
DESCRIPTION OF THE INVENTION
The present invention relates to the use of hydroxycarboxylic acid esters which are obtained by reacting hydroxycarboxylic acids selected from the group consisting of tartaric acid, malic acid and citric acid with fatty alcohol polyglycol ethers corresponding to formula (I):
R
1
O(CH
2
CH
2
O)
n
H (I)
in which R
1
is an alkyl and/or alkenyl group containing 6 to 22 carbon atoms and n is a number of 20 to 150, by methods known per se as thickeners for the production of surface-active formulations.
It has surprisingly been found that the new esters have a strong thickening effect in aqueous surfactant solutions so that a sufficiently high and stable viscosity can even be adjusted in systems that are difficult to thicken, such as for example sugar surfactants of the alkyl glucoside or fatty acid-N-methyl glucamide type. Another advantage of this group of thickeners is that they show high ecotoxicological compatibility and may readily be incorporated in cosmetic or pharmaceutical preparations both in hot and in cold conditions.
Hydroxycarboxylic Acids
Suitable hydroxycarboxylic acids are tartaric acid, malic acid and, in particular, citric acid which may be used in water-free form, but which preferably contain water of crystallization.
Fatty Alcohol Polyglycol Ethers
Fatty alcohol polyglycol ethers which may be used as starting materials for the purposes of the present invention are commercially available addition products of, on average, 20 to 150, preferably 30 to 120 and more preferably 40 to 100 moles of ethylene oxide with technical fatty alcohols containing 6 to 22, preferably 12 to 18 and more preferably 16 to 18 carbon atoms. Typical examples are the corresponding ethoxylates of caproic alcohol, caprylic alcohol, 2-ethylhexyl alcohol, capric alcohol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linolyl alcohol, linolenyl alcohol, eleaostearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and brassidyl alcohol and technical mixtures thereof. Adducts of 40 to 100 moles of ethylene oxide with cetearyl alcohol, tallow fatty alcohol or palm oil alcohol are preferably used.
In overall terms, hydroxycarboxylic acid esters derived from citric acid and fatty alcohol polyglycol ethers corresponding to formula (I), in which R
1
is a C
16-18
alkyl group and n is a number of 40 to 100, are preferred.
Esterification
The esterification of the hydroxycarboxylic acids with the fatty alcohol polyglycol ethers may be carried out in known manner. It is advisable to carry out the reaction in the presence of an acidic catalyst, for example methane sulfonic acid or p-toluene sulfonic acid, which may be used in quantities of 0.1 to 1% by weight and preferably in quantities of 0.2 to 0.7% by weight, based on the starting materials. In addition, to improve the color quality of the reaction products, it has proved to be of advantage to use a reducing agent, for example hypophosphorous acid or sodium hypophosphite, which should be used in a quantity of about 1 to 50% by weight, based on the catalyst. The hydroxycarboxylic acids and the polyglycol ethers are generally used in quantities which correspond to a molar ratio of carboxyl to hydroxyl groups of 1:1 to 3:1 and preferably 2:1 to 2.5:1. The esterification reaction is carried out at temperatures of 100 to 200° C., preferably under reduced pressure. In the case of water-soluble products, the progress of the reaction can be followed via the parameters of acid value and viscosity. The esterification reaction is normally continued until the acid value has fallen to a value below 20 and preferably to a value below 10. However, it is important in this regard to bear in mind that esters with the same acid value can have very different thickening effects. Esters with particularly favorable properties are obtained not only when they meet the low acid value requirement, but also when a 5% by weight sample of the ester in water has a Brookfield viscosity of at least 2,000 mPas, preferably of at least 4,000 mPas and more preferably of at least 7,000 mPas. To produce these preferred esters, heating of the reaction products is continued until a sample shows the required viscosity.
The esters have strong thickening properties and are therefore suitable as thickeners for the production of aqueous surface-active formulations, of which typical examples are liquid detergents, manual dishwashing detergents, fabric softeners and, in particular, cosmetic and pharmaceutical preparations, for example hair shampoos, shower gels, foam baths, hair conditioners, skin lotions, cremes, emollients and the like.
Surfactants
The formulations mentioned above may contain anionic, nonionic, cationic and/or amphoteric or zwitterionic surfactants as further components. Typical examples of anionic surfactants are alkylbenzenesulfonates, alkanesulfonates, olefin sulfonates, alkylether sulfonates, glycerol ether sulfonates, &agr;-methyl ester sulfonates, sulfofatty acids, alkylsulfates, fatty alcohol ether sulfates, glycerol ether sulfates, hydroxy mixed ether sulfates, monoglyceride (ether) sulfates, fatty acid amide (ether) sulfates, mono- and dialkyl sulfosuccinates, mono- and dialkyl sulfosuccinamates, sulfotriglycerides, amide soaps, ether carboxylic acids and salts thereof, fatty acid isethionates, fatty acid sarcosinates, fatty acid taurides, acyl lactylates, acyl tartrat
Bigorra Llosas Joaquim
Pi Subirana Rafael
Prat Queralt Ester
Cognis Deutschland GbmH & Co. KG
Drach John E.
Sharareh Shahnam
Travers Russell
Trzaska Steven J.
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