Study on influencing factors of coil Coating T bending/cupping performance

Coil coating is mainly applied to the surface of metal sheets such as cold-rolled steel sheets, galvanized steel sheets, and galvanized steel sheets by roller coating, and then made into pre-coated coils (referred to as color-coated sheets), which have coating quality. Good, effective, energy saving and environmental protection. Customers process and shape the color-coated sheets into various parts or products, which are widely used in construction, home appliances and automobile industries. Therefore, color-coated sheets are required to have excellent machinability . Usually the machinability of color-coated sheets is characterized by T-bend or cupping tests . The better the T-bend or cupping performance, the better the flexibility of the paint and the easier the color-coated board can be processed. The T-bend reflects the coating's ability to resist cracking or debonding from the metal substrate when the coating is subjected to rapid deformation, while the cupping reflects the coating's resistance to cracking or debonding from the metal substrate under slow stretching ability [1]. T-bend is the deformation of the coating in one dimension , and cupping is the deformation of the coating in two dimensions. Aiming at the T-bending and cupping properties of coil coatings, this paper focuses on the main factors affecting the flexibility of coatings, including: pretreatment, primer/topcoat resin system, and catalysts .

Conclusion

(1) The T-bend and cupping properties of the coating can be significantly improved after the surface treatment of the substrate with a pretreatment solution with a concentration of 5%.

(2) The choice of base resin and curing agent in the primer system has a great influence on the T-bend and cupping of the coating. When the base resin is a linear poly For ester resin, when the curing agent is sealed polyurethane resin BIN-10 and sealed-1, the T-bend and cupping properties of the coating are better.

(3) The addition of branched polyester resin in the matching topcoat system has a great influence on the T-bend and cupping properties of the coating. The amount of branched polyester resin added