Ciba-geigy Corporation

John Burrows

Arthur Harris

James Roger Hargreaves

Thomas Ivor Jones

Peter Miles

Addition compounds of sulfur dioxide and Schiff bases from primary aliphatic or araliphatic amines and aromatic aldehydes can be used for the sealing of the surface of phosphated mild steel. As a result of this the corrosion resistance of the steel and the adhesion of paint coatings on the treated steel are increased substantially. The addition compounds may have three different structures depending on the components used. They can be prepared easily by passing a stream of SO.sub.2 through the solution of the Schiff base.

Corrosion inhibitors

Compositions for inhibiting corrosion and scale formation in aqueous systems which consist essentially of from 20 to 97.5% by weight of total composition of (a) a combination of zinc and hydrolyzed polymaleic anhydride and (b) 2.5 to 80% by weight of total composition of a corrosion inhibitor, particularly benzotriazole.

Treatment of water or aqueous systems

Process for inhibiting corrosion by corrosive water systems on metals which comprises adding to the water systems a phosphonic acid having the general formula: ##STR1## wherein R.sup.1 is a straight chain alkyl group having 1-5 carbon atoms, an alkenyl group having 3-5 carbon atoms in which the double bond is not adjacent to the nitrogen atom, a tolyl group, a benzyl group or a cyclohexyl group.

Corrosion inhibition of water systems with phosphonic acids

Method for inhibiting the corrosion and scale forming tendencies of water or an aqueous system which comprises treating the water or aqueous system with from 0.1 to 500 p.p.m. of an additive combination comprising zinc and hydrolysed polymaleic anhydride.

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Congleton, United Kingdom

John Burrows