Anticorrosive paint for iron and steel - contains a pigment comprising a salt of a polyvalent metal cation and an organic phosphonic acid

摘要

Anti-corrosion coating comprises a pigment salt (I) dispersed in a binder, (I) comprising a polyvalent metal cation (II) and an organic polyphosphonic acid (III) contg. at least two phosphonic acid gps., the mol. ratio of (II) to (III) being at least 0.8/n:1 where n=valency of the metal ion. Pref. (I) has the formula M(x)R(PO3)(m)H(2m-Xn), where M=Zn, Mn, Mg, Ca, Ba, Al, Co, Fe, Sr, Sn, Zr, Ni, Cd or Ti; R=organic radical linked by C-P bonds; m=valency of R (at least 2); n= valency of M and x=0.8 m/n to 2m/n. Process is used for coating iron and steel structural components etc. Coating affords better rusting protection than Zn phosphate whilst avoiding chemicals which are helath hazards.