Adhesion in British
Adhesion is the degree of firmness between the paint film and the coated surface through physical and chemical action. The coated surface can be a bare substrate or a painted substrate
In layman's terms, adhesion refers to the ability of the paint film to bond with the surface of the substrate to be coated or between coatings, also known as adhesion. Adhesion is an important technical indicator and is the premise for the paint film to have a series of performances. The paint film with good adhesion is durable. The paint film with poor adhesion is easy to crack, peeling and cannot be used.
Factors affecting film adhesion include Coating type, hardness of film formation material, finishing process, properties of the surface to be painted and so on.
Coating varieties are different, the film adhesion is different, generally said that the film is softer oil paint, its adhesion is better than the harder Resin paint.
The use of different finishing processes also has an impact on adhesion. When choosing heterogeneous composite coatings, you need to pay attention to the matching of the base and topcoat. For example, when shellac paint was used as a base in the early years, the polyester paint on it was easy to peel off the whole piece; when using the same composite paint layer, some coalescence-type paints (such as polyurethane), when the previous coating is over-drying and then coated with the next paint, the adhesion is affected because the coatings are not well crosslinked. Therefore, in production, when the two-component polyurethane paint needs to be continuously painted many times, it is advisable to use the surface drying and then coating process, that is, the so-called "wet-on-wet" coating process. When reapplying, the surface of the paint film should be sanded or wiped with a solvent and then coated again. Coating.
The surface state of the coated substrate also affects the adhesion, such as the surface of the wood is not clean, there are oil stains, colloids, Resin, dust, etc.; the moisture content of the wood is too high (greater than 15%); and the coating itself is too viscous, which will reduce the adhesion of the paint film.
