This is the basis of the paint, the main substance that makes the paint adhere to the surface of the substrate to become a coating, and the main factor that determines the performance of the paint. It's not paint without it. According to the different film-forming mechanisms, the film-forming substances can be divided into:
1) Solvent volatile
The solvent in the paint evaporates to make the paint dry and form a film (recommended instrument: drying time Tester). There is no chemical reaction in the film forming process, only a physical process.
2) Cross-linked curing type
Among them, the air-dry type refers to the chemical reaction between the coating and certain substances in the air to cross-link and solidify to a film. Such as grease paint and natural resin paint, as well as drying oil in paint (such as tung oil, catalpa oil, perilla oil, linseed oil, etc.), the double bond polymerizes with oxygen in the air due to the automatic oxidation mechanism to form a film during the drying process. Another example is moisture-curing polyurethane paint, which reacts with moisture in the air to form a film.
The other is to cross-link and solidify to form a film through the mutual reaction of two or more film-forming substances in the coating. This is divided into two categories . One is two-pack paint, such as polyurethane paint, epoxy polyamide paint, etc. The former is urethane prepolymer and hydroxyl resin, and the latter is epoxy resin and polyamide (low molecular weight). It can be formed into a film after mixing, and the two components need to be used up within the specified time after mixing, otherwise it will deteriorate (cure) and cannot be used. The other category is bake-cured coatings. Such as amino alkyd baking varnish, acrylic baking varnish, etc. The former film-forming substances are mainly alkyd resin and amino resin. These two components do not react significantly at room temperature. They can be packaged in one can. After construction and coating, they are dried to a certain temperature (related equipment: oven). A chemical reaction occurs, and the cross-linking solidifies to form a film.
Radiation-curing coatings, the main film-forming substance is unsaturated polyester resin, which is cross-linked to form a film under electron beam irradiation.
powder coating. It is divided into two types: thermoplastic (such as polyvinyl chloride, polyethylene, polyamide, fluororesin) and thermosetting (such as epoxy resin, polyester resin, acrylic resin).
