GREEN INHIBITORS FOR COATINGS AND LININGS -- TRADITIONAL Vs. GREEN

摘要

Pigment additives containing chromates, red lead and excessive zinc, commonly used in olden times in paint systems, are toxic and barred from widespread usage. Use of Cr(III) salts instead of Cr(VI) in conversion coatings has been advocated. Methods have been tried to cover the toxic ingredients by non-toxic topcoats and to make them slow leaching by incorporating them in organometallic pigment form strongly bonded to the polymer base of the coating. Zinc phosphate and other zinc salts are being used instead of chromate salts and these are of the green type and offer excellent inhibition in acidic media, in contrast to the chromates that work well in the neutral and alkaline solutions. Green organic inhibitors also have been developed and these include hindered amines having piperidinyl structure and organic phosphate esters. A novel innovation in the antifouling marine coating area is the use of fouling agents themselves, such as green algae and tubeworms, to retard fouling and corrosion of steel.