Composition for use nox removing translucent coating
The presente invention concerns a NO x removing composition for use as a translucent coating on construction material surface, comprising at least: a) photocatalytic titanium dioxide particles having at least a de-NO x activity, b) particles having a de-HNO 3 activity, and c) a silicon based-material in which said particles are dispersed, wherein said photocatalytic particles have a crystalline size ranging from 1 to 50 nm and particles of a) and b) being present in an amount lower than 20% by weight of the total weight of said composition.
1 . A NO x removing composition for use as a translucent coating on construction material surface, comprising at least:
a) photocatalytic titanium dioxide particles having at least a de-NOx activity,
b) particles having a de-HNO3 activity, and
c) a silicon based-material in which said particles are dispersed, wherein said photocatalytic particles have a crystalline size ranging from 1 to 50 nm and particles of a) and b) being present in an amount lower than 20% by weight of the total weight of said composition.
2 . The composition according to claim 1 , wherein photocatalytic particles include at least anatase form of titanium oxide, rutile form of titanium oxide or a mixture thereof.
3 . The composition according to claim 3 , wherein the titanium dioxide particles are predominantly the anatase crystalline form.
4 . The composition according to claim 3 , wherein the crystalline titanium dioxide particles exhibit a mean size from 1 to 50 nm, in particular from 2 to 30 nm, more particularly from 5 to 20 nm.
5 . The composition according to claim 1 , wherein the photocatalytic particles have a surface area per gram higher than 30 m 2 /g.
6 . The composition according to claim 1 , wherein the photocatalytic particles are present in an amount of 0.1 to 15%, preferably 1 to 12%, and most preferably 2 to 10% by weight (expressed in dry matter) of the total weight of said composition.
7 . The composition according to claim 1 , wherein de-HNO3 particles include basic compounds.
8 . The composition according to claim 7 , wherein de-HNO3 particles include calcium carbonate, zinc carbonate or a mixture thereof.
9 . The composition according to claim 8 , wherein the de-HNO3 particles are present in an amount of 0.05 to 15%, in particular of 0.1 to 1% by weight of the total weight of said composition.
10 . The composition according to claim 1 , wherein it includes photocatalytic titanium dioxide and de-HNO3 particles in a ratio de-HNO3 particles/titanium dioxide particles ranging from 0.05 to 1.2, in particular from 0.1 to 1, and more particularly from 0.2 to 0.8.
11 . The composition according to claim 1 , wherein the silicon based-material provides a polysiloxane film.
12 . The composition according to claim 1 , wherein the silicon based-material includes at least a polysiloxane polymer.
13 . The composition according to claim 1 including furthermore a solvent.
14 . A method for imparting self-cleaning properties towards atmospheric contaminants to the surface of a material, said method comprising at least the steps of:
applying a composition according to claim 1 onto the surface of a material, and
drying or curing the composition to obtain a transparent coating thereon.