| 摘要 |
<p>1399417 Pre-paint coating constituent DIAMOND SHAMROCK CORP 17 Oct 1973 [18 Oet 1972] 48401/73 Heading C4A A precursor constituent for a pre-paint coating composition containing pulverulent zinc used to support corrosion resistance to metal substrates, comprises an aqueous medium, chromic acid, a compatible pH adjustment agent and xanthan gum hydrophilic colloid, the chromic acid being present in an amount sufficient to provide a pH in water of below 3 and the pH adjustment agent being present in amount sufficient to give the precursor constituent a pH of 3 to 6. The pH adjustment agent may be an oxide or hydroxide of a metal other than Na, K, Rb or Cs which is soluble in the aqueous chromic acid solution. A reducing agent for the hexavalent chromium provided by the chromic acid may be present, e.g. a dicarboxylic acid also containing succinimide, acrylamide or aspartic acid. Tertiary alcohols and/or chlorinated hydrocarbons may be added to the aqueous medium.</p> |
