Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1998-01-15
2001-02-20
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S061000, C424S064000, C424S070700
Reexamination Certificate
active
06190677
ABSTRACT:
The present invention relates to the improvement of the photochromic properties of an initially photochromic compound, and to its application in the field of cosmetic compositions, in particular.
Cosmetic compositions, in particular make-up compositions such as free or compact powders, foundations, blushers or eye-shadows, lip compositions or nail varnishes, comprise a suitable vehicle and various colorants intended to impart some degree of color to the compositions before and/or after they are applied to the skin, the mucous membranes, the mucocutaneous tissues and/or parts of the exoskeleton, for example the nails or the hair.
A fairly limited range of colorants is presently used to create colors, in particular lakes, inorganic pigments or pearlescent pigments. Lakes allow vivid colors to be obtained, but are for the most part unstable with respect to light, temperature or pH. Some of them also have the drawback of staining the skin unattractively after they have been applied, as a result of the colorant being leached. Conversely, inorganic pigments, in particular inorganic oxides, are highly stable but give somewhat dull and pale colors. In order to obtain colored effects, use may also be made of pearlescent pigments whose colors are varied, albeit never intense, which make it possible to obtain iridescent but most often fairly weak effects.
It has therefore been proposed to use photochromic compounds in make-up or haircare compositions, so as to obtain attractive and varied changes in the color effect of make-up for the skin and/or the hair.
Photochromic compounds are compounds which have the property of changing color when they are exposed to a light source, then of returning to their initial color, or a similar color, when they are no longer being exposed. In particular, compounds of this type have a particularly advantageous application in cosmetic compositions, in particular in make-up compositions such as foundations and blushers or eye-shadows. Indeed, it has been found that the make-up effect of skin which has been made up differs depending on whether the illumination is natural or artificial. Thus, make-up applied under artificial illumination will appear lighter under natural light. Conversely, make-up applied out of doors will appear darker in a place where the illumination is artificial.
The photochromic properties of a compound can be characterized using two parameters, calculated on the basis of measuring the trichromatic coordinates (L, a and b), in the following way.
A compound which initially has the coordinates (L0, a0, b0) will be considered.
The compound is firstly exposed to a light source for 30 minutes under standard conditions, then the new coordinates (L30, a30 and b30) are measured, these coordinates reflecting the color change due to the exposure. A first parameter &Dgr;E30 can be calculated which reflects the ability of a compound to take on a color different from the original one:
&Dgr;E30=[(L30−L0)
2
+(a30−a0)
2
+(b30−b0)
2
]
½
The compound which has been exposed for 30 minutes is secondly placed in complete darkness for 30 minutes, then the new coordinates (L60, a60 and b60) are measured.
A second parameter &Dgr;E60 can be calculated which reflects the color change with respect to the situation before exposure:
&Dgr;E60=[(L60−L0)
2
+(a60−a0)
2
+(b60−b0)
2
]
½
The value &Dgr;(&Dgr;E), equal to the absolute value of the difference between &Dgr;E60 and &Dgr;E30, reflects the capacity of a compound to return, after exposure and darkness, to a color similar to that of the initial state, that is to say before exposure.
The prior art has, in particular, proposed the use in cosmetics of organic photochromic compounds, for example compounds of the spiropyran or naphthoxazine families.
These photochromic compounds are particularly advantageous since they enable the support to which they are applied to change color rapidly when the support is exposed to UV, for example, with rapid return to the initial color when it is no longer being exposed to UV.
Mention may thus be made of French Patent Application FR 1 604 929, which describes cosmetic compositions, in particular for the hair, in aerosol form which contain phototropic compounds such as nitrobenzylpyradines, thiosemi-carbazones or spiropyran derivatives. After these compositions have been sprayed onto the hair and exposed to sunlight, a blue-violet coloration is obtained which returns to pale yellow in darkness.
Cosmetic compositions comprising particular inorganic photochromic compounds, selected from metal oxides, their hydrated forms and their complexes, have also been proposed, for example by European Patent Application EP 359 909. In particular, this document mentions the use of titanium oxide, treated so as to make it photochromic, in make-up compositions such as powders and foundations.
Further, U.S. Pat. No. 5,176,905 discloses a process for obtaining a photochromic titanium oxide by mixing iron hydroxide (FeOOH) and titanium dioxide, and calcining at 750-850° C.
In addition, European Patent Application EP 624 553 discloses a process for preparing titanium oxide having improved photochromism, this process involving dissolving an organotitanium compound and an organic compound comprising at least one metal, in an organic solvent, then in hydrolysing the mixture, recovering the hydrolysate and in calcining it at a temperature of 550-700° C. This produces a photochromic titanium oxide having a color difference which can be quantified using the parameter &Dgr;E, the value of which is at least 10. The value &Dgr;E is the measured difference between the chromaticity before exposure and the chromaticity after exposure for 1 hour, under UV at 2 mW/cm
2
.
Furthermore, Japanese Patent Application JP 05/017152 discloses a process for preparing a photochromic titanium oxide, involving mixing organotitanium compounds with at least one metal selected from iron, chromium, copper, nickel, vanadium or manganese, then in sintering the mixture in the presence of sodium compounds. It is thus possible to obtain a parameter &Dgr;E which is improved in comparison with the prior art, and is in particular greater than 10. The parameter &Dgr;E is calculated in the same way as in EP 624 553.
In the latter two documents, the improved parameter &Dgr;E reflects the ability of a compound to change color when exposed to light. This document makes absolutely no mention of any improvement of the parameter &Dgr;(&Dgr;E), which reflects the ability of the compound to return to a state similar to the initial state.
However, it has been observed that, even though they make it possible to obtain an appreciable change in the color of the make-up, that is to say a relatively large &Dgr;E, the prior art photochromic compounds, in particular the inorganic compounds, nevertheless have the following drawback: when it is no longer being exposed to light, the color of the make-up does not always return acceptably to its initial color, and in particular does not return completely to a color identical to the initial color. After a cycle of exposure and darkness, the photochromic compound has a color substantially different from its initial color before exposure. The “relaxation of the photochromic compound in the dark” can thus be considered as weak or low. For these compounds, this is characterized by a small value of &Dgr;(&Dgr;E), of the order of 3-4.
The object of the present invention is to provide a particular process for improving photochromism, in particular improving the value &Dgr;(&Dgr;E) of an initially photochromic compound, while maintaining a satisfactory value &Dgr;E30, that is to say one which is at least of equal value, and often improved, that is to say as high as possible.
The present invention therefore relates to a process for preparing a photochromic compound having a parameter &Dgr;(&Dgr;E) greater than or equal to 7, in which a photochromic compound of the metal oxide, hydrated metal oxide or metal oxide and/or h
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Howard S.
L'Oreal
Page Thurman K.
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