Cosmetic compositions with agglomerated substrates

Details Cosmetic compositions with agglomerated substrates Cosmetic compositions with agglomerated substrates

2000-01-31

2001-10-30

Dees, Jos′ e G. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S401000, C424S709000, C424S489000

Reexamination Certificate

active

06309627

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to cosmetic compositions containing agglomerates with particular particle sizes.
2. The Prior Art
It is well known that inorganic particles such as e.g. oxides like iron oxides, titanium dioxide, zinc oxide etc. in cosmetic emulsions tend to form agglomerates of various sizes. Consequently, application of such emulsions to the skin can be disagreeable if large agglomerates first have to be dispersed by rubbing. The problem increases with diminishing particle size of the products applied. It is therefore often necessary to counteract such agglomerate formation with other additives.
From EP-B-406657, lamellar substrates are known comprising at least 0.5% wt spherical particles with a small-diameter of approx. 0.05 to 50 &mgr;m when compared to the lamellar substrates. A stated particular advantage of the invention is the occurrence of deagglomeration of the lamellar substrates as a result of the addition of spherical particles of e.g. SiO
2
, TiO
2
and ZrO
2
.
Furthermore, WO 96/17588 states that by adding SiO
2
to kaolin which also forms lamellar substrates, an increase in the kaolin content in cosmetic compositions is made possible.
EP-A-704502 describes the improvement of the protective effect of ZnO by dispersion in an alkali metal silicate solution gelled by the addition of CO
2
, whereby SiO
2
containing ZnO is obtained.
SUMMARY OF THE INVENTION
It is thus the object of the present invention to develop cosmetic compositions with very good spreading characteristics on the skin, without the agglomeration of inorganic particles such as oxides having a disagreeable effect.
Surprisingly, it was found that the addition of spherical, non-porous SiO
2
particles of a particular particle size to other essentially spherical particles does not cause any deagglomeration, but results in defined agglomerates whose particle size is particularly advantageous for cosmetic preparations because these compositions allow very homogenous spreading on the skin, show very good reflection of UV radiation and in cosmetic sunscreen preparations with TiO
2
and/or ZnO achieve at least equal sunscreen factors as is the case with known sunscreen preparations, while achieving higher stability of the sunscreen factor (SPF).
The invention thus provides for the preparation of cosmetic compositions with agglomerated substrates comprising a content of spherical and porous SiO
2
particles, with the SiO
2
particles comprising a particle size ranging from 0.05 &mgr;m to 1.5 &mgr;m, where apart from the SiO
2
particles other inorganic particle-shaped materials of spherical structure are present, with the spherical SiO
2
particles forming defined agglomerates with other inorganic materials, with a particle size ranging from 0.06 &mgr;m to 5 &mgr;m. The proportion of agglomerates in the cosmetic composition ranges from 0.1 to 30% wt.
The agglomerated substrates are further characterised in that they are produced by mixing the spherical non-porous SiO
2
particles with the other inorganic particle-shaped materials of spherical structure present dry or as an oily dispersion with a viscosity of 13,500 to 200,000 cps, individually or mixed, maintaining a pH value of 5.5 to 7 such that part of the total water is to be added until a paste-like consistency is attained, with stirring for 20 to 100 minutes, with the remaining water subsequently being added while the pH value is maintained and homogenisation taking place at 3,000 to 5,000 rpm; with the temperature during the mixing processes ranging from 35 to 48° C. The dispersion obtained is then worked into the cosmetic composition in the usual manner with the proportion of agglomerates in the cosmetic composition being between 0.1 and 30% wt.
Of particular advantage is the use of highly monodispersed non-porous spherical SiO
2
particles according to DE3616133 produced by hydrolytic polycondensation of tetraalkoxysilane in an aqueous-alcoholic-ammoniacal medium, with a sol being produced from primary particles and subsequently the SiO
2
particles obtained being reduced to the desired particle size of approx. 0.05 to 10 &mgr;m by controlled adding, depending on the reaction process, of tetraalkoxysilane.
However, it is also possible to use SiO
2
particles produced according to other processes as far as they are non-porous and spherical, and comprise the respective particle size. If the use of TiO
2
in the composition is desired, particles may be used which comprise approx. 80% SiO
2
and 20% TiO
2
.
The other inorganic particle-shaped materials of spherical structure used in the cosmetic composition according to the invention are mostly oxides such as iron oxides, e.g. Fe
2
O
3
, Fe
3
O
4
, FeO or mixed oxides; titanium dioxide; zinc oxide; zirconium dioxide; pigments; or magnetically hard single-grade particles (single-crystals) made of barium hexaferrite or strontium hexaferrite with a high corrective field intensity of 4,000 to 5,000 Oersted according to WO 95/03061.
Further pigments may for example be selected from among mica, kaolin, talcum, nylon globules, ceramic globules, expanded and non-expanded synthetic polymer powders, powdery natural organic compounds such as ground solid algae, encapsulated and non-encapsulated cereal starches as well as addition products comprising organic dyes.
In the context of the present invention, the term “inorganic spherical particles” denotes a round, spherical to at most ellipsoid shape of the particles.
The proportion of the agglomerates in the entire composition can range from 0.1 to 30% wt, preferably 0.5 to 25% wt.
Depending on the desired effect of the other inorganic particle-shaped materials, their ratio in respect of each other can vary widely. If e.g. in the case of sunscreen preparations, protection against UV-A radiation is emphasised, the ratio of TiO
2
:ZnO can range from 1:1 to 1:10. By contrast, if the emphasis is on protection against UV-B radiation, the ratio of TiO
2
:ZnO can range from 100:1 to 20:1.
The ratio TiO
2
:SiO
2
or ZnO:SiO
2
can generally be between 100:1 and 1:1, preferably 20:1 to 2:1.
In a combination of TiO
2
/ZnO/SiO
2
, the ratio TiO
2
:ZnO:SiO
2
can range from 1:100:1 to 100:1:1.
The ratio of other inorganic particle-shaped materials to SiO
2
can be between 100:1 to 1:1.
Apart from the agglomerates defined according to the invention, the composition may comprise usual cosmetic adjuvants or active substances in a proportion from 99.9 to 70% wt.
Cosmetic active-ingredients include e.g. emulsifiers, inorganic and organic sunscreen agents, radical interceptors, moisturisers, vitamins, enzymes, active vegetable substances, polymers, melanin, antioxidants, natural anti-inflammatory substances, oxygen-laden asymmetric lamellar aggregates according to WO 94/00109; digestion products of yeasts or vegetable substances made by a gentle ultrasonic digestion process according to WO 94/13783, kaolin as well as kaolin modified by SiO
2
according to WO 94/17588.
Cosmetic adjuvants include water, various vegetable oils, mineral oil, silicon oil, gelatinising agents, dyes, preservatives, perfume, monovalent and polyvalent alcohols, protectants, pH regulators, waxes etc.
In the case of cosmetic preparations according to the invention, comprising TiO
2
and/or ZnO, sunscreen factors are obtained which with the same content of active substances are at least equivalent to those known from conventional sunscreen preparations, e.g. from EP-B-433086 which describes a synergistic TiO
2
/ZnO combination claiming TiO
2
of less than 35 nm and ZnO of less than 50 nm, optionally containing TiO
2
at 2 to 25% wt. With 24.5% TiO
2
and 10% ZnO, the sunscreen factor according to Cole and VanFossen should have a value of 32 and the composition should have an aesthetic appearance.
However, with a sunscreen protection factor which is at lest equivalent, the sunscreen preparations according to the invention provide a better stability of the sunscreen factor, i.e. the effect is longer lasting. This has been proven beyond doubt in several tr

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