| abstract |
Anticorrosive coating compositions comprise a binding polymer and an amorphous aluminum phosphate corrosion inhibiting pigment. The composition comprises from about 1 to 25 percent by weight amorphous aluminum phosphate. The amorphous aluminum phosphate has a water adsorption potential of up to about 25 percent by weight water. The composition provides a controlled phosphate delivery of from about 50 to 500 ppm, and preferably of from about 100 to 200 ppm. The composition has a total solubles content of less than about 1,500 ppm. The amorphous aluminum phosphate is preferably substantially free of alkali metals. The amorphous aluminum phosphate is made by combining aluminum hydroxide with phosphoric acid and sodium aluminate. The amorphous aluminum phosphate is treated to reduce the level of unwanted solubles, and the treated amorphous aluminum phosphate is dried at less than about 300° C. The composition is used as a primer coat, a mid-coat, and/or a top-coat coating. |