Stable inorganic pigment prodn. by coating with amorphous silica - pptd from alkali silicate soln. as sol with specified reagent, useful in paint, plastics etc.

摘要

Prodn. of a stable inorganic pigment (I) involves reacting an alkali silicate (II) with cpd(s). (III) reacting with (II) to form an amorphous silica sol (iv) and/or with acid gas(es) (V) in an aq. suspension of an inorganic pigment (VI) at pH 7-11 (8-11) and min. 60 (70-100) degrees C (and atmos. pressure), so that (IV) is pptd. on the surface of the (VI) particles. (III) is an organic acid (deriv.), P oxy-acid, borate or phosphate ester, alkali or ammonium salt, boric acid or ethylene carbonate. The (VI) suspension is prepd. pref. by hydrothermal treatemtn with alkali. (VI) can have a coting of fine amorphous hydrated Zr, Al, Ti, Ce, Sb or Mg oxide. (III) has a solubility of min. 0.01 g/100 gH2O at 200 degrees C and pH min. 1.0 in 3 wt.% aq. soln. Specified (III) are carboxylic, sulphonic and amino acids, phenols and their salts, esters, amides aldehydes, anhydrides and peroxides; phosphoric acid; NaHSO4, NaHSO3, NaHCO3, NaH2PO4; NC4Cl, NH4NO3, (NH4)2SO, NH4HSO4 (NH4)2SO3, NH4HSO3, (NH4)2CO3, NH4HCC3 and NH4H2PO4. (V) is CO2, SOx or NOy (in which x = 1-4 and y = 0.5-3). (VI) is a chromate, Fe, Ti or Pb oxide, Ca, Ba or Mg salt, Co, Mn, Cd, metal powder, cinnabar, Sb2O3, ZnO, viridina, Cr oxide green or ultramarine pigment. (I) has good pigment properties, i.g. high chemical stability, resistance to H2S, light, weathering and heat and storage, stability. It is useful in paints, printing inks, plastics, rubbers, building materials, cosmetics and paper.