Self-cleaning polymers
The present invention relates to a mixture, comprising at least one thermoplastic polymer as component (A) and at least one photocatalytically active particle, comprising a non-porous core comprising at least one metal oxide or semimetal oxide with a diameter of from 0.1 nm to 1 μm, and, at least to some extent surrounding the core, at least one porous outer layer comprising at least one further metal oxide or further semimetal oxide with an average layer thickness of from 0.1 to 10 nm, as component (B), to a process for the production of this mixture according to any of claims 1 to 5 , via mixing of components (A) and (B), to the use of the mixture as photocatalytically active surface, to moldings, comprising this mixture, and to the use of this mixture for the production of moldings.
1. A mixture comprising:
(A) at least one styrene-acrylonitrile copolymer, and
(B) at least one photocatalytically active particle, comprising a non-porous core comprising at least one metal oxide or, semimetal oxide of metals and semimetals selected from the group consisting of V, Ti, Zr, Ce, Mo, W, Bi, Zn, Mn, Si, Ba, Au, Ag, Pd, Pt, Ru, Rh, La, and mixtures thereof, with a diameter of from 1 nm to 200 nm, and, at least 70% surrounding the core, at least one porous outer layer comprising at least one further metal oxide or further semimetal oxide selected from SiO 2 , ZnO, CeO 2 , TiO 2 , SnO, SnO 2 and mixtures thereof, with an average layer thickness of from 0.1 to 10 nm,
wherein the ratio of proportion of metal or semimetal in the outer layer in atomic percent to proportion of the metal or semimetal in the core, in atomic percent, amounts to from 2 to 80.
2. The mixture according to claim 1 , wherein the (B) at least one photocatalytically active particle has a core composed of TiO 2 and an outer layer composed of SiO 2 .
3. The mixture according to claim 2 , wherein the TiO 2 is present in the anatase form.
4. The mixture according to claim 1 , which comprises additives, auxiliaries, or further substances.
5. The mixture according to claim 1 , which comprises from 75 to 99.5% by weight of the at least one styrene-acrylonitrile copolymer as component (A), from 0.5 to 25% by weight, based in each case on the entire mixture, of at least one photocatalytically active particle, comprising a non-porous core comprising at least one metal oxide or semimetal oxide with a diameter of from 1 to 200 nm, and, at least 70% surrounding the core, at least one porous outer layer comprising at least one further metal oxide or further semimetal oxide with an average layer thickness of from 0.1 to 10 nm, as the (B) at least one photocatalytically active particle, where the total of the amounts of the (A) at least one styrene-acrylonitrile copolymer and the (B) at least one photocatalytically active particle, is 100% by weight.
6. A process for the production of the mixture according to claim 1 comprising: mixing the (A) at least one styrene-acrylonitrile copolymer and the (B) at least one photocatalytically active particle and of any additives, auxiliaries, or further substances present.
7. The process according to claim 6 , wherein the mixing is carried out at a temperature of from 80 to 350° C.
8. A molding comprising the mixture according to claim 1 .