Sunscreen compositions comprising a mixture of titanium and/or z

Details Sunscreen compositions comprising a mixture of titanium and/or z Sunscreen compositions comprising a mixture of titanium and/or z

1997-09-15

1999-08-17

Dodson, Shelley A.

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

106425, 106428, 106436, 2523131, 2523154, A61K 742, A61K 700, C09C 104, C09C 136

Patent

active

059390549

DESCRIPTION:

BRIEF SUMMARY
The subject of the invention is sunscreen compositions based on titanium oxide and/or on zinc oxide. It is also targeted at a method for producing them and at their cosmetic and therapeutic use in protecting the skin against all the effects of ultraviolet radiation A and B.
It is known to use titanium oxide (TiO.sub.2) and/or zinc oxide (ZnO) as agents for reflecting ultraviolet rays.
By way of examples, Patents EP 91 304 100, GB 87/17662 or WO 89/01438 describe sunscreen compositions containing titanium oxide as agent for protecting against radiation.
In the same way, Patents EP 535 972 and WO 92/13517 describe sunscreen compositions containing zinc oxide as agent for protecting against radiation.
Patents FR 2 591 480 and EP 833 086 describe, for their part, sunscreen compositions containing a combination of the two oxides. It appears that this combination has a synergic effect on the value of the sun protection factor. This combination is consequently shown to be particularly advantageous in the production of sunscreen compositions.
However, the compositions thus obtained might be further improved. This is because it would be beneficial to increase their stability and in particular the homogeneity of the particle dispersion. Their protective power might also be further optimized.
The aim of the invention is to provide a sunscreen composition based on titanium oxide and/or on zinc oxide which is better in quality than those already existing as regards:
Success has been achieved, according to the invention, by employing zinc oxide particles and/or titanium oxide particles incorporated in paste-forming oils and/or esters and/or fatty alcohols and/or ethers selected with the aim of producing: point for the incorporated zinc oxide particles which are less than approximately 5, for the incorporated zinc oxide particles which are less than approximately 30.
The amount by weight of petrolatum to be added to a mixture of 9 g of particles and 7 g of paste-forming oil in order to produce complete wetting of the powders and a fluid paste respectively is called the wetting point and the flow point respectively of the incorporated particles.
Incorporation of the TiO.sub.2 particles is understood to mean the operation which consists in predispersing, by milling, the said particles in a choice of oils and/or of esters and/or of fatty alcohols and/or of ethers with hyperdispersing qualities, so that, after milling the particles and the oils and/or the esters and/or the fatty alcohols and/or the ethers in a triple roll mill or bead mill, a stable white paste is obtained which can be directly included in the industrial process. Incorporation prevents any reagglomeration of the particles which may be responsible for the fall in the photoprotection on the skin of the finished product.
The particles, thus predispersed in this mixture of oils and/or of esters and/or of fatty alcohols and/or of ethers, without an emulsifying agent, change from the cake and agglomerate state (of more than 100 microns) to an ideal monodispersed and monocrystalline form (15 to 30 nm).
As regards the TiO.sub.2, this ready-for-use paste for the industrial process is different from commercial suspensions and titanium oxide powders, such as TioVeil (Tioxyde): the white paste is obtained without addition of subsidiary surface-active compounds and of organic compounds.
The incorporation of the ZnO particles is of the same nature as that of TiO.sub.2 particles.
It may also be possible to employ zinc oxide particles, such as, for example, those of Spectraveil type, sold by Tioxyde, without ever combining it with TIOVEIL (TIOXYDE), an acicular titanium oxide suspension.
The combination of the two oxides incorporated in oils and/or esters and/or fatty alcohols and/or ethers in accordance with the invention results in a synergic effect on the protection factor, whereas the same combination, without incorporation, does not give rise to this synergy.
Advantageously, the titanium oxide particles exhibit a size of less than or equal to 20.+-.5 nm and the zinc ox

REFERENCES:
patent: 5366660 (1994-11-01), Tapley
patent: 5573753 (1996-11-01), Tapley
patent: 5605652 (1997-02-01), Tapley

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