Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-11-09
2004-03-09
Kim, Vickie (Department: 1614)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C514S242000
Reexamination Certificate
active
06703001
ABSTRACT:
The present invention relates to cosmetic and dermatological light protection formulations, in particular skincare cosmetic and dermatological light protection preparations.
The harmful effect of the ultraviolet part of solar radiation on the skin is generally known. While rays with a wavelength of less than 290 nm (the so-called UVC region) are absorbed by the ozone layer in the earth's atmosphere, rays in the range between 290 nm and 320 nm, the so-called UVB range, cause erythema, simple sunburn or even burns of varying severity.
The maximum given for the erythema activity of sunlight is the narrower range around 308 nm.
Numerous compounds are known for protecting against UVB radiation; these are usually derivatives of 3-benzylidenecamphor, of 4-aminobenzoic acid, of cinnamic acid, of salicylic acid, of benzophenone and also of 2-phenylbenzimidazole.
It is also important to have available filters for the range between about 320 nm and about 400 nm, the so-called UVA region, since its rays can likewise cause damage. Thus, it has been found that UVA radiation leads to damage of the elastic and collagenous fibers of connective tissue, causing premature aging of the skin, and that it is to be regarded as a cause of numerous phototoxic and photoallergic reactions. The harmful effect of UVB radiation can be intensified by UVA radiation.
However, UV radiation can also lead to photochemical reactions, in which case the photochemical reaction products intervene in the skin's metabolism.
Such photochemical reaction products are predominantly free-radical compounds, e.g. hydroxyl radicals. Undefined free-radical photoproducts which form in the skin itself can also display uncontrolled secondary reactions because of their high reactivity. However, singlet oxygen, a non-radical excited state of the oxygen molecule, can also arise during UV radiation, as can short-lived epoxides and many other species. Singlet oxygen, for example, differs from the normal triplet oxygen (free-radical ground state) by virtue of its increased reactivity. However, excited reactive (free-radical) triplet states of the oxygen molecule also exist.
Furthermore, UV radiation is a type of ionizing radiation. There is therefore the risk that UV exposure may also produce ionic species which then, for their part, are capable of oxidative intervention in the biochemical processes.
An advantageous UVB filter is tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, also known as 2,4,6-tris-[anilino(p-carbo-2′-ethyl-1′-hexyloxy)]-1,3,5-triazine.
This UVB filter is sold by BASF Aktiengesellschaft under the trade name UVINUL7 T 150 and is notable for its good UV absorption properties.
The main disadvantage of this UVB filter is its poor solubility in lipids. Known solvents for this UVB filter can dissolve a maximum of about 15% by weight of this filter, corresponding to about 1-1.5% by weight of dissolved, and therefore active, UV filter substance.
It was nevertheless surprising, and could not have been foreseen by the person skilled in the art, that active ingredient combinations comprising tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate and one or more esters of branched-chain carboxylic acids and branched-chain alcohols, or the use of one or more esters of branched-chain carboxylic acids and branched-chain alcohols as solvent, solubility promoter or solubilizer for tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, in particular for the use in light protection compositions, would overcome the disadvantages of the prior art.
The esters of branched-chain carboxylic acids and branched-chain alcohols according to the invention can advantageously be chosen from the group of substances of the general formula
in which R
1
and R
2
, independently of one another represent mono- or polybranched alkyl radicals having 3 to 30 carbon atoms.
R
1
is advantageously a mono- or polybranched alkyl radical having up to 10 carbon atoms.
In addition, R
2
is advantageously a mono- or polybranched alkyl radical having 5 to 20 carbon atoms.
It is particularly advantageous to use neopentanoic esters as carboxylic esters used according to the invention.
It is very particularly advantageous to use isodecyl neopentanoate as carboxylic ester used according to the invention. It has the chemical structure
and is entered in the Chemical Abstracts under the registry number 60209-82-7. It is sold, for example, by Stearinerie Dubois under the name DUB VCI 10. As is known, it may be used in cosmetic and dermatological preparations as oil component.
It was nevertheless surprising that the addition of one or more esters of branched-chain carboxylic acids and branched-chain alcohols effects stabilization of solutions of tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, since the latter substance not only has poor solubility, but also readily crystallizes out again from its solution. The invention therefore also provides a method of stabilizing solutions of tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, which comprises adding an effective content of one or more esters of branched-chain carboxylic acids and branched-chain alcohols to such solutions.
The total amount of tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate in the finished cosmetic or dermatological preparations is advantageously chosen from the range 0.1-10.0% by weight, preferably 0.5-6.0% by weight, based on the total weight of the preparations.
The total amount of one or more esters of branched-chain carboxylic acids and branched-chain alcohols in the finished cosmetic or dermatological preparations is advantageously chosen from the range 0.1-25.0% by weight, preferably 0.5-15.0% by weight, based on the total weight of the preparations.
It is advantageous to choose weight ratios of tris(2-ethylhexyl) 4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate and one or more esters of branched-chain carboxylic acids and branched-chain alcohols from the range 1:10 to 10:1, preferably 1:4 to 4:1.
Cosmetic and dermatological preparations according to the invention also advantageously comprise inorganic pigments based on metal oxides and/or other metal compounds which are sparingly soluble or insoluble in water, in particular the oxides of titanium (TiO
2
), zinc (ZnO), iron (e.g. Fe
2
O
3
), zirconium (ZrO
2
), silicon (SiO
2
), manganese (e.g. MnO), aluminum (Al
2
O
3
), cerium (e.g. Ce
2
O
3
), mixed oxides of the corresponding metals and mixtures of such oxides. Pigments based on TiO
2
are particularly preferred.
For the purposes of the present invention, it is particularly advantageous, although not imperative, if the inorganic pigments are present in hydrophobic form, i.e. they have been surface-treated to repel water. This surface treatment can consist in providing the pigments with a thin hydrophobic layer by processes known per se.
One such process consists, for example, in producing the hydrophobic surface layer by the reaction according to:
n
TiO
2
+m
(RO)
3
Si—R′6
n
TiO
2
(surf.)
where n and m are arbitrary stoichiometric parameters and R and R′ are the desired organic radicals. Hydrophobicized pigments prepared analogously to DE-A 33 14 742, for example, are advantageous.
Advantageous TiO
2
pigments are available, for example, under the trade names MT 100 T from TAYCA, also M 160 from Kemira and T 805 from Degussa.
The cosmetic and/or dermatological light protection formulations according to the invention can have the conventional compositions and can be used for cosmetic and/or dermatological light protection, and also for the treatment, care and cleansing of the skin and/or hair and as make-up products in decorative cosmetics.
For use, the cosmetic and dermatological preparations according to the invention are applied to the skin and/or hair in sufficient amount and in the manner conventional
Gers-Barlag Heinrich
Kröpke Rainer
LandOfFree
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