Transparent or translucent emulsions, process for preparing...

Details Transparent or translucent emulsions, process for preparing... Transparent or translucent emulsions, process for preparing...

2002-05-06

2003-09-09

Dees, Jose′ G. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S070100, C424S070900, C424S400000, C424S401000, C514S844000, C514S957000

Reexamination Certificate

active

06616917

ABSTRACT:

The present invention relates to transparent or translucent emulsions which are preferably of the oil-in-water (O/W) or water-in-oil (W/O) type based on at least one volatile fluoro compound, to a process for their preparation and to their use in cosmetics.
The present invention relates most particularly to cosmetic emulsions intended in particular for skincare, hair conditioning, antisun protection and/or artificial tanning.
As is known, emulsions consist essentially of two immiscible phases, one being fatty and the other aqueous, and of a surfactant whose role is to stabilize the dispersion of one of the phases, which is present in the form of dispersed droplets, in the continuous phase. Depending on the proportion of the two phases in the emulsion, it is said to be of the oil-in-water type when the aqueous phase is the continuous phase, or of the water-in-oil type when the fatty phase is the continuous phase.
Emulsions are commonly used in cosmetics since they offer great flexibility in formulations and in cosmetic applications. Specifically, they can include a wide variety of active ingredients of very different nature and can be in various forms such as creams or gels that vary in fluidity or thickness.
However, these emulsions generally have a whitish appearance and consequently users find them relatively unappealing. This appearance results essentially from phenomena of deviation by refraction and reflection of the light rays at the interface of the two phases. This opacity is particularly observed in the case of antisun products, since certain sunscreens have high refractive indices, which accentuates the deviation phenomena.
Various processes have been envisaged in order to minimize the deviation of light rays and thus increase the transparency of the compositions.
Among these processes, mention may be made of processes which consist in reducing the diameter of the droplets of the dispersed phase of the emulsion, either by phase inversion, which is found, however, to be difficult, or by adding high proportions of surfactants and treatment in a high-pressure machine. However, in the latter case, the microemulsions thus obtained have the drawback of causing certain skin discomfort and irritation reactions, thus making them cosmetically unacceptable, due essentially to the excess surfactant.
A process has also been proposed which consists in increasing the refractive index of the aqueous phase by adding glycol or glycerol, so as to bring its refractive index closer to that of the fatty phase. However, this process requires the addition of an often large proportion of glycol or glycerol and the emulsions thus obtained have genuinely unpleasant aspects such as a sticky cosmetic feel, as well as problems of discomfort when they are applied.
Moreover, the addition of glycol or glycerol may not be sufficient to obtain compositions with good transparency, due to the generally high refractive index of certain sunscreens.
It is moreover known practice to prepare transparent antisun or self-tanning compositions in the form of aqueous or aqueous-alcoholic gels; however, liposoluble sunscreens cannot be used in aqueous gels and these gels are only very sparingly water-resistant.
As for the aqueous-alcoholic gels, they have the drawback of containing high proportions of alcohol, in particular ethanol, which raises technical problems during their formulation.
It has now been found, surprisingly and unexpectedly, that it is possible to obtain excellent transparent or translucent emulsions by reducing the refractive index of the fatty phase in order for it to be substantially equal to that of the aqueous phase, this being achieved by using a miscible volatile fluoro compound with a refractive index of less than or equal to 1.3.
A subject of the present invention is thus a transparent or translucent emulsion comprising an aqueous phase, a fatty phase and a surfactant, characterized in that the fatty phase contains a miscible mixture of at least one cosmetic oil and of at least one volatile fluoro compound, the latter compound being present in a proportion such that the refractive index of the fatty phase is equal to ±0.05 of that of the aqueous phase, preferably equal to ±0.03 and more preferably equal to ±0.01.
According to the invention, the expression “transparent or translucent emulsion” means an emulsion whose matrix allows light to pass through without causing any deviation by refraction or reflection, or causing only small deviations of the light rays at the interface of the two phases. If the transparency of an emulsion can be readily evaluated with the naked eye, it is generally measured using a turbidimeter. The portable turbidimeter model 2100P® from the company Hach can be used, for example, to measure the ranges of transparency of the emulsions according to the present invention. These emulsions are said to be transparent when the value measured is between 0 and 250 NTU, while they are said to be translucent for a value ranging from 250 to 1000 NTU.
According to the invention, the term “miscible” should be understood as meaning that the mixture is in homogeneous form, i.e. no dephasing takes place between the constituents after they have been placed in contact.
According to the invention, the expression “cosmetic oil” should be understood as meaning any cosmetically acceptable fatty substance that is liquid at 25° C.
The volatile fluoro compound in the fatty phase, used as a mixture with at least one cosmetic oil, is preferably selected from the following compounds:
1) perfluorocycloalkyls corresponding to formula (I) below:
in which:
n is 2, 3, 4 or 5
m is 1 or 2, and
p is 1, 2 or 3
with the proviso that when n=2, m is 2 and when n=3, 4 or 5 and m=2, the fluoro groups are not necessarily alpha to each other;
2) perfluoroalkanes corresponding to formula (II) below:
CF
3
—(CF
2
)
m
—CF
2
X  (II)
in which:
m is an integer between 2 and 8, and
X represents Br or F;
3) fluoroalkyls or heterofluoroalkyls corresponding to formula (III) below:
CH
3
—(CH
2
)
n
—[Z]
t
—X—CF
3
  (III)
in which:
X is a linear or branched perfluoroalkyl radical containing from 2 to 5 carbon atoms, and
Z is O, S or NR, R being a hydrogen or a —(CH
2
)
n
—CH
3
or —(CF
2
)
m
—CF
3
radical, m being 2, 3, 4 or 5, n is 0, 1, 2 or 3 and t is 0 or 1, and
4) perfluoromorpholine derivatives corresponding to formula (IV) below:
in which R is a C
1
-C
4
perfluoroalkyl radical.
Among the perfluorocycloalkyls of formula (I) which may be mentioned in particular are perfluoromethylcyclopentane and perfluoro-1,3-dimethylcyclohexane, which are sold under the names “Flutec PC1®” and “Flutec PC3®” by the company BNFL Fluorochemicals Ltd. and perfluoro-1,2-dimethylcyclobutane.
Among the perfluoroalkanes of formula (II) which may be mentioned, inter alia, are dodecafluoropentane and tetradecafluorohexane, sold under the trade names “PF5050®” and “PF5060®” by the company 3M or alternatively bromoperfluorooctyl sold under the trade name “Foralkyl®” by the company Atochem.
Among the fluoro compounds of formula (III) which may be mentioned, for example, is nonafluoromethoxybutane and nonafluoroethoxybutane sold respectively under the trade names “HFE-7100®” and “HFE-7200®” by the company 3M.
Finally, among the perfluoromorpholine derivatives of formula (IV) which may be mentioned, for example, is 4-trifluoromethylperfluoromorpholine sold under the trade name “PF5052®” by the company 3M.
These volatile fluoro compounds which have just been defined above all have a refractive index (n
D
20
) of less than 1.43, preferably less than 1.40 and most particularly less than 1.36; they preferably have a saturating vapour pressure, at 25° C., at least equal to 50 Pa; furthermore, they have a boiling point generally of between 25° C. and 65° C. and a high density generally of greater than 1, preferably of greater than 1.2.
The volatile fluoro compound is present in the fatty phase such that the refractive index of the said phase is preferably less than 1.36, it

Affiliated with

Also associated with

Rating

Transparent or translucent emulsions, process for preparing... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Transparent or translucent emulsions, process for preparing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transparent or translucent emulsions, process for preparing... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3076402