METHOD FOR TREATMENT OF METAL SHEETS AND METAL SHEETS TREATED BY THIS METHOD
Patent Information
- Application Number
- MA50350
- Authority / Receiving Office
- MA · MA
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2018-09-14
- Filing Date
- 2018-09-14
- Publication Date
- 2020-08-19
- Estimated Expiration
- 2038-09-14
AI Technical Summary
The existing surface treatment methods for zinc-coated metal sheets, particularly those involving zinc hydroxysulphate, result in inadequate adhesion with epoxy-based adhesives due to the reactivity of hydroxyl groups and the presence of free water molecules, which degrades the interfacial bonds and leads to adhesion issues in the automotive industry.
A surface treatment process that forms a zincsulphate-based conversion layer on a steel substrate by controlling the air drying temperature, strip velocity, wet film thickness, initial strip temperature, and air flow rate to exclude zinc hydroxysulphate, free water molecules, and free hydroxyl groups, favoring the formation of stable zincsulphate monohydrate, tetrahydrate, or heptahydrate, thereby enhancing adhesion with epoxy-based adhesives without compromising corrosion resistance.
The process ensures strong adhesion with epoxy-based adhesives while maintaining the corrosion resistance and drawability of the metal sheets, as demonstrated by improved lap shear test results and resistance to degradation over time.