Coating film formation mainly includes two aspects of coating adhesion and coating drying.
A paint adhesion
The first step in the adhesion of the steel strip substrate and the paint is the wetting of the paint on the substrate surface. The wetting of the paint can replace the air and water originally adsorbed on the surface of the steel strip substrate , and at the same time, the solvent volatilizes on the substrate surface to dissolve or swell. , if the film -forming resin of the coating and the solubility parameters of the substrate surface are properly selected, a mixed layer will be formed between the substrate surface and the coating film , which is very important for the good adhesion of the coating.
B coat dry
In the coating process of the color-coated board, the adhesion construction of the paint only completes the first step of the film formation of the paint, and the process of becoming a solid continuous film must be continued to complete the entire film-forming process of the paint. This process from "wet film" to "dry film" is often called "drying" or "curing". This drying and curing process is the core of the coating film forming process. Coatings with different . Usually we divide the film formation of coatings into two categories:
(1) Non-conversion type. Generally refers to the physical film-forming method, that is, mainly depends on the volatilization , and the viscosity of the coating film gradually increases to form a solid coating film. For example: acrylic paint, chlorinated rubber paint, vinyl paint, etc.
(2) Conversion type. It generally refers to the chemical reaction that occurs during the film formation process, and the coating mainly relies on the chemical reaction to form the film . This kind of film formation is the process in which the film-forming substances in the paint polymerize the coating film called polymer after construction. It can be said to be a special polymer synthesis method, which completely follows the polymer synthesis reaction mechanism. For example: alkyd coatings, epoxy coatings , polyurethane coatings, phenolic coatings, etc. However, most modern coatings do not form a film in a single way, but rely on multiple ways to form a film. Coil coating is a typical one that relies on multiple ways to form a film.
