Reasons for peeling and delamination of the zinc-rich primer and polyurethane topcoat applied on the surface of the equipment’s metal protective layer after six months of use

The reasons for peeling and delamination may include: 1. Improper surface treatment: If the surface of galvanized iron sheet is not cleaned properly and contains oil, dust, or other impurities, it will affect the adhesion of the coating. 2. Poor compatibility between primer and topcoat: Zinc-rich primers may have compatibility issues with polyurethane topcoats, resulting in the inability to form a strong coating. 3. Environmental factors: High temperatures, humidity, or extreme weather conditions can also accelerate the aging of coatings, leading to peeling and delamination. To prevent peeling and extend the service life of the coating, the following measures can be taken: 1. Surface treatment: Ensure that the metal surface is thoroughly clean and dry; if necessary, apply appropriate surface texturing to enhance adhesion. 2. Choose the right primer: Select a primer that is compatible with the polyurethane topcoat and is specifically designed for galvanized iron sheets, in order to improve the overall performance of the coating. 3. Consider environmental factors: Choose coating products that are suitable for the local environmental conditions, such as those with properties like moisture resistance and UV protection. 4. Proper application: Follow the manufacturer’s instructions for applying the coating, and properly control the time and conditions for each step to ensure that the coating cures fully. .

Another possibility is that the use of an incompatible curing agent or thinner is to blame.

Judging from the picture, it’s because the metal surface has no roughness, resulting in poor adhesion.

Galvanized surfaces are relatively smooth, and paint does not adhere well to them