Cleaning with alkali adhesion

For formation of anticorrosive and adhesion-improving protective layers on metals the cleaned surface is treated with aqueous acidic solution containing molybdate, chromium fluoride, phosphate, acetate, and Zn ions. As dispersant a mixture of 60% alkali salt of a phosphate ester, 20% alkylpolyglucoside, and 20% fatty alcohol ethoxylate was applied. This method passivates the metal surface by formation of an anticorrosive and protective layer that improves adhesion of subsequent coatings. 

SEM-BEI, X20 (Fe-IOCr) with ChlorOut. Significantly better adhesion in metal/oxide interface with lower Cl content. A few spots with high Cl content were detected, again with no connection to detectable alkali contents. Massive FeS-layers were detected. (A clean signal from these layers typically gave 45%S-49%Fe in atomic%.). 

Solution vehicles consist of water soluble polymers not manufactured by emulsion polymerization. The solution vehicle is an alkali soluble polymer in aqueous solution or a blend of polymers with combined properties into a single waterborne varnish. Soluble polymers are made by free radical polymerization in a processing solvent or as addition or condensation products with heat reaching temperatures up to 265 °C. Solution vehicles are mixtures of soluble resins unlike emulsion polymers. A solution vehicle is used to increase adhesion to film and improve ink printabihty or transfer to meet specific performance requirements. The solution vehicle provides pigment dispersion stabilization, transparency, low film forming temperature, gloss and re-solubility. An alkali soluble resin is a carboxylic acid functional polymer neutralized (solubilized) with ammonia, amine or sodium hydroxide. The add numbers are generally above 100. Ammonia or volatile amines are used in most aqueous inks except for news print inks. After evaporation of the amine, the resin becomes insoluble and resistant to water spray or other water contact. The ink is re-solubilized with alkaline water for the clean-up cycle. For news print ink, the polymers are solubiHzed with sodium hydroxide to maintain re-solubility (open time) of the ink on the press. News print ink pressman prefer unlimited open time and fewer clean-up cycles. Water resistance is not required since ink penetrates the news print paper fibers. 

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