Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-11-09
2004-08-03
Hartley, Michael G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000, C514S242000
Reexamination Certificate
active
06770269
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 socalled 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 unbranched-chain carboxylic acids and branched-chain alcohols, or the use of one or more esters of unbranched-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 unbranched-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
is an unbranched-chain alkyl radical having 3 to 30 carbon atoms, and R
2
represents mono- or polybranched alkyl radicals having 3 to 30 carbon atoms.
R
1
is advantageously an unbranched-chain alkyl radical having up to 20 carbon atoms.
In addition, R
2
is advantageously a mono- or polybranched alkyl radical having up to 25 carbon atoms.
For the purposes of the present invention, the carboxylic ester(s) is/are very particularly advantageously present in a mixture with the parent alcohols R
2
—OH.
It is particularly advantageous to use hexyldecyl laurate, for example in a mixture with hexyldecyl alcohol as the carboxylic ester used according to the invention. Such a mixture is entered in the Chemical Abstracts under the registry numbers 70693-04-8 and 34362-27-1 and is sold, for example, by Henkel KGaA under the name Cetiol®PGL. As is known, it can be used in cosmetic and dermatological preparations as an oil component.
It was nevertheless surprising that the addition of one or more esters of unbranched-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 unbranched-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 unbranched-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 unbranched-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 dermatolo
Gers-Barlag Heinrich
Kröpke Rainer
Beiersdorf AG
Hartley Michael G.
Lamm Marina
Norris McLaughlin & Marcus PA
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