MODIFIED STARCH, AQUEOUS SOLUTION OF A MODIFIED STARCH AND PROCESS FOR PRETREATING STEEL SURFACES

摘要

The invention provides a process of improving the corrosion resistance of metal surfaces by treating the metal surfaces with an aqueous solution of a modified polysaccharide containing from 0.1 to 0.9 anionic groups per monosaccharide unit and from 0.1 to 2.0 C1-C6 alkyl or alkanoyl groups per monosaccharide unit. The modified polysaccharide has a relatively high molecular weight of between 30 kDa and lO MDa.