Protection of the surfaces of building materials of monuments, statues, sculptural decoration, inscriptions, polychromes, murals, pictures and new buildings from the effect of atmospheric pollutants by coating with a new system of semiconductors produced by a new method as pigments in reversible polymers.

摘要

The invention consists of protection by dressing or spraying the surfaces of building materials of monuments, new buildings, statues, sculptural decoration, inscriptions, polychromes, murals and pictures from attack by atmospheric pollutants: acid rain, sulphuration (gypsum formation) and deposits of suspended particles with a solution of preferably reversible (re-soluble) polymers that contain a semiconductor. Thus the invention consists of dressing or spraying the above surfaces with a solution of a reversible polymer that contains an n-semiconductor such as: Al2O3, Al(OH)3, TiO2, Ti(OH)4, Fe2O3, Fe(OH)3 etc., characterized as MxOyHz (where x=1,2,3, y=1,2,3,4 and z=0,1,2,3,4) plain or doped with, for example, MgO or other substances and of a cheap and improved method for preparation of such semiconductors. The final ratio of solid polymer:n-semiconductor = 98- 50:2-50. The method for preparation of these semiconductors consists of precipitation of the hydroxides of the metals with 0.001 to 1M alkali solutions from 0.001 to 1M aqueous solutions of any of their salts, filtration and washing with deionized or distilled water until the anions of the original salts are completely removed (testing with an appropriate reagent), drying of the hydroxides at 40 degree - 110 degree C, firing at 400 degree - 900 degree C to convert them to the oxide (if they are to be used as such and not as the hydroxide) and grinding. To prepare mixtures (doped) of the same n-semiconductors, any salt of magnesium or another metal is added to the initial solution of salts in a final ratio of: MxOyHz: (e.g.) MgO or Mg(OH)2 = 1-5:1-0.3. Measurement of the electrical resistance of the powder is carried out to test intensity of the n-semiconductivity. The n-semiconductor prepared by this method is then added to a solution of, preferably, a reversible (re-soluble) polymer as above and the resulting mixture used to dress or spray the surface for protection. Other than the considerable protection of the above surfaces against atmospheric attack offered by the addition of the semiconductor (pure or doped) it also leads to the surfaces being protected from cracking from corrosion with mechanical fatigue and protection by the polymers from ultraviolet radiation and repulsion of suspended particles and micro-organisms. The semiconductors are not consumed as materials nor are their n-semiconducting properties exhausted.