| 摘要 |
<p>An aqueous composition substantially free of strontium chromate comprises (A) an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersible or emulsifiable epoxy resin, (B) chromium trioxide, and (C) water. The aqueous compositions may also contain other ingredients including zinc and/or ferro alloys. Alternatively, an aqueous composition comprises (A) at least one water-dispersible or emulsifiable epoxy resin, (B) chromium trioxide, (C) water, and (D) zinc powder or a ferro alloy powder or a mixture thereof. These aqueous compositions are useful as pretreatment coatings on metal surfaces, and in particular, on steel and on galvanized and aluminized metal substrates. This pretreatment coating can then be coated with weldable or non-weldable primer coatings followed by the application of decorative topcoat such as appliance topcoats or automotive topcoats.</p> |
