| abstract |
COLORED NACREOUS PIGMENTS ARE PROVIDED BASED ON MICA FLAKES COATED WITH TWO SUPERIMPOSED LAYERS, THE FIRST LAYER BEING TITANIUM AND/OR ZIRCONIUM OXIDE MIXED WITH ANOTHER METALLIC OXIDE, THE LATTER BEING PREFERABLY AN OXIDE HAVING AN INHERENT COLOR, E.G. IRON OXIDE. THE SECOND LAYER CONSISTS SOLELY OF TITANIUM AND/OR ZIRCONIUM OXIDE AND IS ABOUT TWICE AS THICK AS THE FIRST COATING. THE PIGMENTS ARE PRODUCED BY FEEDING INTO AN AQUEOUS SUSPENSION OF MICA FLAKES AT A SUBSTANTIALLY CONSTANT TEMPERATURE BETWEEN ABOUT 50 AND 100*C. AND AT A SUBSTANTIALLY CONSTANT PH BETWEEN 0.5 AND 5.0: (A) AN AQUEOUS METALLIC SALT SOLUTION CONSISTING ESSENTIALLY OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF A TITANIUM SALT, A ZIRCONIUM SALT AND MIXTURES THEREOF, SAID MEMBER BEING IN A CONCENTRATION OF 0.01-4.0 MOL/LITER, SAID ANOTHER SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, CHROMIUM, NICKEL, COBALT, ANTIMONY, ALUMINUM, SILICON, TIN, BISMUTH, AND A MIXTURES THEREOF, SAID OTHER SALTS BEING IN A TOTAL CONCENTRATION OF 0.02-1 MOL/LITER, SAID SOLUTION HAVING A CONTENT OF FREE ACID CORRESPONDING TO A MOLARITY OF 0.002-3; (B) AFTER THE FEEDING OF SOLUTION (A), FEEDING AN AQUEOUS, 0.01 TO 4 MOLAR MOLAR SOLUTION CONSISTING ESSENTIALLY OF ONLY A MEMBER SELECTED FROM THE GROUP CONSISTING OF A TITANIUM SALT, A ZIRCONIUM SALT, AND MIXTURES THEREOF, SAID SOLUTION HAVING A CONTENT OF FREE ACID CORRESPONDING TO A MOLARITY OF 0.002-3; (C) SIMULATNEOUSLY WITH THE FEEDING OF BOTH (A) AND (B), PASSING INTO THE SUSPENSION AN AQUEOUS, 0.025TO 10-MOLAR BASIC SOLUTION OF A BASE SELECTED FROM THE GROUP CONSISTING OF AN ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, OR AN EQUIVALENT AMOUNT OF GASEOUS AMMONIA; WITH THE PROVISIONS THAT: (D) THE AMOUNT OF SALT FED PER MINUTE IS APPROXIMATELY 0.01-25.10**-5 MOL PER M.2 OF MICA SURFACE, (E) THE THICKNESS OF THE METALLIC OXIDE LAYER PRECIPITATED BY SOLUTION (A) AMOUNTS TO ABOUT ONE-THIRD OF THE TOTAL COATING THICKNESS OF THE PRECIPITATED OXIDE LAYERS. |