Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1999-02-08
2001-05-22
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S063000
Reexamination Certificate
active
06235295
ABSTRACT:
This application is a 371 of PCT FR9800467 filed Mar. 9, 1998.
The present invention relates to a process for the manufacture of a solid composition using plaster, and to a composition, in particular a cosmetic composition, obtained by this process.
It is known practice to manufacture cosmetic compositions in solid form using plaster. These cosmetic compositions can be, in particular, eyeshadows, blushers, face powders or body powders. They can be in the form of sticks, pencils or cakes. The use of plaster to manufacture these solid compositions is described, for example, in patent U.S. Pat. No. 4,724,138. According to the known processes, a pulverulent phase containing plaster is mixed with an aqueous phase in order to obtain a paste which is shaped by moulding, the hydration reaction of the plaster (calcium sulphate hemihydrate) into calcium sulphate dihydrate leading to solidification of the composition. The use of plaster as a solidification agent is advantageous since it replaces the compacting operation, which is usually needed to obtain a composition in solid form from pulverulent products, with a moulding operation which is easier and less expensive to carry out and allows a wider range of forms to be obtained.
Moreover, it is common practice to add preserving agents to cosmetic compositions, with the aim of giving the composition good conservation, in particular to prevent the proliferation of microorganisms in the composition.
Preserving agents can be incorporated into plaster-based compositions in different ways. They can be added either to the pulverulent phase comprising the plaster, or to the aqueous phase before mixing these two phases together to form the castable paste. Thus, in patent U.S. Pat. No. 4,724,138, methyl para-hydroxybenzoate is added to the powder phase. Patent application WO 86/00798 proposes, for its part, to incorporate the preserving agents into the aqueous phase.
The Applicant has observed that when the preserving agents are added to the aqueous phase, the concentration of these preserving agents is not uniform in the final composition obtained after the water has been evaporated off, since there is a concentration gradient of the preserving agents in the final composition. The preserving agents are thus found to be concentrated towards the evaporation surface of the composition. Protection of the composition against the growth of microorganisms is thus not identical in all parts of the composition. In addition, when the composition is a make-up product, for example a blusher, application to the skin of that part of the composition containing the highest concentration of preserving agent can give rise to problems of tolerance of the composition on the skin: skin irritation or stinging can then be caused by too high a concentration of preserving agents in the composition applied.
It has also been observed that the concentration gradient of the preserving agents is also formed when a preserving agent in powder form is added, irrespective of the phase into which it is introduced.
The present invention is aimed at overcoming these drawbacks and proposes a process for the preparation of a composition, in particular a cosmetic composition, which makes it possible to obtain a uniform distribution of the preserving agents in the final composition. The term uniform distribution is understood to mean that the concentration of preserving agents is more or less constant in all parts of the final composition.
The Applicant has discovered, surprisingly and unexpectedly, that the use of a liquid preserving system makes it possible to obtain a composition with a uniform distribution of the preserving agent(s).
The subject of the present invention is thus a process for the preparation of a plaster-based solid composition, this process comprising the following steps:
a pulverulent mixture comprising at least calcium sulphate hemihydrate in powder form is prepared,
an aqueous phase is added to the pulverulent mixture,
the pulverulent mixture and the aqueous phase are blended together so as to obtain a castable mixture,
the castable mixture is poured into a mould,
the mixture is left to cure by hydration of the calcium sulphate hemihydrate into calcium sulphate dihydrate,
characterized in that before adding the aqueous phase, a non-aqueous liquid preserving system comprising at least one preserving agent having a water-solubility of less than or equal to 0.5% at 25° C. (weight/weight percentage) is added to the pulverulent mixture, the said liquid preserving system having a viscosity of less than or equal to 4.5 Pa.s.
The invention also relates to a composition, in particular a cosmetic composition, which can be obtained by the process according to the invention. The composition thus obtained is entirely suitable for make-up. It can be used as a blusher, an eyeshadow or a face powder.
The invention also relates to a plaster-based solid cosmetic composition comprising a preserving system uniformly distributed in the said composition, the said preserving system being, when not in the composition, in the form of a non-aqueous liquid comprising at least one preserving agent having a water-solubility of less than or equal to 0.5% at 25° C., the said liquid preserving system having a viscosity of less than or equal to 4.5 Pa.s at 25° C.
The term preserving agent is understood to refer to any compound having antimicrobial and/or antioxidant action. A preserving agent having antimicrobial action is preferably used.
According to the present patent application, the expression non-aqueous liquid preserving system is understood to refer either to one or more preserving agents whose mixture is liquid at 25° C., or to one or more liquid or solid preserving agents, as a mixture with a non-aqueous solvent, the mixture being liquid at 25° C.
Preferably, the liquid preserving system according to the invention has a viscosity of less than 3 Pa.s at 25° C. and more preferably less than 1.5 Pa.s at 25° C.
The viscosity of the liquid preserving agent according to the invention can be measured, for example, on a Rheomat RM115 viscometer from Contraves, with a suitable rotor (for example MSDIN 108, 114, 125), at a shear rate of 221.3 5 s
−1
, after 10 minutes.
It is necessary for the preserving system not to be aqueous, since the addition of the preserving agent to an aqueous phase does not give uniform distribution of the preserving agent in the final composition.
The liquid non-aqueous solvent according to the invention is any liquid compound which is compatible with the preserving agent, it being possible for the preserving agent or the mixture of preserving agents either to be dissolved, partially or totally, or to be dispersed uniformly in the said solvent at least at the time of use, i.e. the preserving agent or the mixture of preserving agents is well distributed in the solvent at the time of preparation of the mixture. Preferably, in particular when the preserving agent or the mixture of preserving agents is in powder form, the preserving agent or the mixture of preserving agents is dissolved, partially or totally, in the solvent. Thus, the mixture of preserving agent and of solvent should have the required viscosity according to the invention. The solvent for the preserving system is chosen such that it does not have a negative impact on the antimicrobial and/or antioxidant activity of the preserving agent.
Advantageously, a solvent for the preserving agent can be used which gives a solution of the preserving agent in the solvent (total dissolution of the preserving agent in the solvent). The preserving agent mixed with the said solvent is not necessarily liquid at 25° C. It can, in particular, be in powder form, but its water-solubility at 25° C. must be less than 0.5% (weight/weight percentage), preferably less than 0.4% and more preferably less than 0.35%.
Advantageously, a preserving system can be used comprising a preserving agent/solvent mixture in a preserving agent/solvent weight ratio ranging from about 10/90 to 90/10, and preferably from 20/80 to 40/60.
As liq
Bodelin-LeComte Sophie
Le Gars Guénola
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
L'Oreal (S.A.)
Page Thurman K.
Ware T.
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