Particulate UV protection agent
View Patent ↗The present invention relates to particulate UV protection agents which are obtainable by hydrothermal treatment of a particulate metal oxide and subsequent application of a manganese oxide coating, and to the preparation and use thereof. The present invention furthermore relates to novel compositions, in particular for topical application, which are intended, in particular, for light protection of the skin and/or hair against UV radiation and free-radical-induced stress, and to the use thereof in the above-mentioned cosmetic application.
1. A UV protection agent, where the UV protection essentially emanates from a particulate metal oxide, comprising a particulate metal oxide, which is titanium dioxide,
wherein
the crystallite size of the particulate titanium dioxide in the particulate UV protection agent, determined by the Scherrer method, is 8 to 50 nm, and the dimensions of the particulate titanium dioxide, which can be determined in a transmission electron microscope, are a length of 20 to 60 nm and a width of 8 to 30 nm, and
the titanium dioxide carries a first coating consisting essentially of aluminum compounds and a second coating consisting essentially of one or more manganese compounds.
2. A UV protection agent according to claim 1 , wherein the one or more manganese compounds are selected from the group consisting of the oxides, hydroxides, phosphates, sulfates and fatty acid salts of manganese.
3. An aqueous or oily dispersion comprising a particulate UV protection agent according to claim 1 and water or an oil.
4. A composition having light-protection properties comprising a carrier and at least one UV protection agent according to claim 1 .
5. A composition having light-protection properties according to claim 4 , which is suitable for the protection of body cells against oxidative stress, for reducing skin ageing, and which optionally comprises one or more antioxidants.
6. A UV filter comprising a carrier and a particulate UV protection agent according to claim 1 .
7. A process for preparing a particulate UV protection agent according to claim 1 , comprising
a) subjecting a particulate titanium dioxide to hydrothermal treatment and
b) subsequently applying a first coating consisting essentially of aluminum compounds and a second coating consisting essentially of one or more manganese compounds.
8. A process according to claim 7 ,
wherein step a) is carried out in a sealed container at 40 to 360° C.;
or
wherein step b) is carried out as a sol-gel process, in which a manganese sulfate solution is optionally added to a suspension of the titanium dioxide;
or
wherein step b) is carried out at a pH kept constant in the range from pH=2 to pH=11;
or
wherein step b) is carried out at elevated temperature;
or
wherein a hydrophobicising layer is applied in an aftertreatment.
9. A process for preparing a composition according to claim 4 , comprising mixing said entity with a cosmetically or dermatologically suitable vehicle.
10. A UV protection agent according to claim 1 , which possesses the property of a spin concentration of 25 to 40% after having been combined with 2,2-diphenyl-1-picrylhydrazyl for three minutes, wherein said property has been measured by spectra recordation on a Bruker E500 X Band cw spectro-meter at room temperature.
11. A food comprising a UV protection agent according to claim 1 .
12. A UV protection agent according to claim 1 , wherein the titanium dioxide is doped with a metal.
13. A UV protection agent according to claim 1 , wherein the titanium dioxide is doped with Fe.
14. A cosmetic composition, comprising a cosmetically acceptable carrier and a UV protection agent according to claim 13 .
15. A cosmetic composition, comprising a cosmetically acceptable carrier and a UV protection agent according to claim 1 .