Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
1999-03-19
2001-03-27
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000
Reexamination Certificate
active
06207140
ABSTRACT:
This application is a 371 of PCT/EP97 05349 filed Sep. 29, 1997
BACKGROUND OF THE INVENTION
This invention relates to sun protection compositions in the form of o/w microemulsions containing oils, selected anionic emulsifiers and UV filters and to the use of these mixtures for the production of sun protection compositions.
PRIOR ART
Under the influence of solar radiation, the pigmenting of normal skin leads to the formation of melanins. Exposure to long-wave UV-A light results in darkening of the melanins present in the epidermis without any harmful effects while exposure to short-wave UV-B radiation results in the formation of new melanin. However, before the protective pigment can be formed, the skin is exposed to the effect of unfiltered radiation which can lead to reddening of the skin (erythema), inflammation of the skin (sunburn) or even to blisters, depending on the exposure time. The strain on the organism associated with such skin lesions, for example in connection with the distribution of histamines, can additionally lead to headache, lassitude, fever, heart and circulation problems and the like. The consumer seeking to protect himself/herself against the harmful effects of the sun can choose from a range of products which, for the most part, are oils and milky emulsions which, besides a few skin-care ingredients, contain above all UV filters. Overviews on this subject have been published, for example, by P. Finkel in Parf. Kosm. 76, 432 (1995) and by S. Schauder in Parf. Kosm. 76, 490 (1995).
Nevertheless, there is a continuing need on the market for products with an improved performance spectrum. Of particular interest in this regard are compositions which enable relatively large amounts of UV filters to be incorporated without any phase separation or sedimentation occurring during storage. Where relatively large quantities of titanium dioxide are incorporated, a formulation produced by the phase inversion temperature method, as described for example in European patent application EP-A1 0 667 144 (L'Oreal), tends to separate the dispersed solid very quickly. Another problem is that many UV filters are capable of interacting with the other ingredients of the formulation, resulting in a chemical reaction and also in a reduction in storage stability. Finally, consumers prefer transparent formulations which show high skin-cosmetic compatibility, even when applied to very sensitive skin. Accordingly, the complex problem addressed by the present invention was to provide sun protection compositions which would be distinguished at one and the same time by particular phase stability, stability in storage, transparency and compatibility with sensitive skin.
DESCRIPTION OF THE INVENTION
The present invention relates to sun protection compositions in the form of o/w microemulsions containing
(a) oils,
(b) monoglyceride (ether) sulfates and
(c) UV filters.
It has surprisingly been found that o/w microemulsions of the described type are extremely stable in storage, even where relatively large quantities of UV filters are incorporated, and are distinguished by particularly high skin-cosmetic compatibility. In addition, their particle fineness makes them transparent which contributes towards the aesthetic appearance of the products. The invention includes the observation that particularly advantageous compositions can be obtained by using mixtures of (b1) monoglyceride sulfates and (b2) alkyl ether sulfates, alkyl oligoglucosides and/or fatty acid-N-alkyl glucamides in a ratio by weight of 10:90 to 90:10 and preferably 25:75 to 75:25 as emulsifiers.
Oils
Suitable oils are, for example, Guerbet alcohols based on fatty alcohols containing 6 to 18 and preferably 8 to 10 carbon atoms, esters of linear C
6-20
fatty acids with linear C
6-20
fatty alcohols, esters of branched C
6-13
carboxylic acids with linear C
6-20
fatty alcohols, esters of linear C
6-18
fatty acids with branched alcohols, more particularly 2-ethyl hexanol, esters of linear and/or branched fatty acids with polyhydric alcohols (for example dimer diol or trimer triol) and/or Guerbet alcohols, triglycerides based on C
6-10
fatty acids, vegetable oils, branched primary alcohols, substituted cyclohexanes, Guerbet carbonates, dialkyl ethers and/or aliphatic or naphthenic hydrocarbons. Other suitable oils are silicone compounds, for example dimethyl polysiloxanes, methylphenyl polysiloxanes, cyclic silicones and amino-, fatty-acid-, alcohol-, polyether-, epoxy-, fluorine- and/or alkyl-modified silicone compounds which may be both liquid and resin-like at room temperature. The oils may be present in the compositions according to the invention in quantities of 1 to 90% by weight, preferably 5 to 75% by weight and more preferably 10 to 50% by weight, based on the non-aqueous component.
Monoglyceride (ether) Sulfates
Monoglyceride sulfates and monoglyceride ether sulfates are known anionic surfactants which may be obtained by the relevant methods of preparative organic chemistry. They are normally produced from triglycerides which are transesterified to the monoglycerides, optionally after ethoxylation, and then sulfated and neutralized. The partial glycerides may also be reacted with suitable sulfating agents, preferably gaseous sulfur trioxide or chlorosulfonic acid [cf. EP-B1 0561825, EP-B1 0561999 (Henkel)]. If desired, the neutralized products may be subjected to ultrafiltration to reduce the electrolyte content to the required level [DE-A1 4204700 (Henkel)]. Overviews of the chemistry of monoglyceride sulfates have been published, for example, by A. K. Biswas et al. in J. Am. Oil. Chem. Soc. 37, 171 (1960) and by F. U. Ahmed in J. Am. Oil. Chem. Soc. 67, 8 (1990).
The monoglyceride (ether) sulfates to be used in accordance with the present invention correspond to formula (I):
in which R
1
CO is a linear or branched acyl group containing 6 to 22 carbon atoms, x, y and z together stand for 0 or for numbers of 1 to 30, preferably 2 to 10, and X is an alkali metal or alkaline earth metal. Typical examples of monoglyceride (ether) sulfates suitable for the purposes of the invention are the reaction products of lauric acid monoglyceride, cocofatty acid monoglyceride, palmitic acid monoglyceride, stearic acid monoglyceride, oleic acid monoglyceride and tallow fatty acid monoglyceride and ethylene oxide adducts thereof with sulfur trioxide or chlorosulfonic acid in the form of their sodium salts. Monoglyceride sulfates corresponding to formula (I), in which R
1
CO is a linear acyl group containing 8 to 18 carbon atoms, are preferably used. The percentage content of monoglyceride (ether) sulfates is normally from 10 to 90% by weight, preferably from 25 to 75% by weight and more preferably from 40 to 60% by weight, based on the non-aqueous component.
Alkyl Ether Sulfates
Alkyl ether sulfates (“ether sulfates”) which may be used as anionic co-emulsifiers are known surfactants which, on an industrial scale, are produced by SO
3
or chlorosulfonic acid (CSA) sulfation of fatty alcohol or oxoalcohol polyglycol ethers and subsequent neutralization. Ether sulfates suitable for use in accordance with the invention correspond to formula (II):
R
2
O—(CH
2
CH
2
O)
m
SO
3
X (II)
in which R
2
is a linear or branched alkyl and/or alkenyl radical containing 6 to 22 carbon atoms, n is a number of 1 to 10 and X is an alkali metal and/or alkaline earth metal, ammonium, alkylammonium, alkanolammonium or glucammonium. Typical examples are the sulfates of addition products of on average 1 to 10 and more particularly 2 to 5 moles of ethylene oxide onto 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, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and brassidyl alcohol and technical mixtures thereof in the form of their sodium and/or magnesium salts. The ether sulfates may have both a con
Fabry Bernd
Kahre Joerg
Seipel Werner
Cognis Deutschland GmbH
Dodson Shelley A.
Drach John E.
Trzaska Steven J.
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