The working principle of primer

The working principle of primers is mainly reflected in the following aspects:

Improving paint adhesion: As the first layer of a coating system, the primary purpose of a primer is to enhance the adhesion between the paint and the substrate.

The fillers and binders added to the primer firmly bond the paint film to the substrate, thereby reducing paint film peeling or flaking.

By improving the paint's permeability and wetting properties, the primer allows the paint to penetrate as much as possible into the pores and cracks of the substrate. After curing, it forms numerous tiny anchors that firmly hold the substrate, thus improving the adhesion of the coating film.

Filling surface defects: The fillers in the primer can fill surface defects on the substrate, such as scratches, dents, or cracks, making the substrate surface smooth and even.

This prevents subsequent coatings from making surface defects more noticeable and affecting the overall effect.

Mechanical and chemical bonding: The working mechanism of primers also includes mechanical and chemical bonding.

Mechanical bonding improves adhesion through the physical interlocking between the primer and the substrate.

Chemical bonding occurs when the active groups in the primer react with atoms or groups on the substrate surface to form chemical bonds, thereby enhancing adhesion.

Improving van der Waals forces and reactive groups: Primers can also improve the van der Waals forces between the coating and the substrate. By increasing the wettability of the coating on the substrate, it allows the coating to fully wet and adhere to the substrate surface before curing, thus improving van der Waals forces and ultimately enhancing the adhesion of the coating film to the substrate.

Primers can also increase reactive groups, such as amino, hydroxyl, and carboxyl groups, creating conditions for the formation of hydrogen bonds and chemical bonds, further improving adhesion.

Diffusion effect: When the substrate being coated is a polymer substrate, the primer can promote the mutual diffusion and dissolution of coating and substrate molecules, ultimately leading to the disappearance of the interface, thereby improving the adhesion between the coating film and the substrate.

In summary, primers improve coating effects through various means, including enhancing adhesion between the coating and the substrate, filling surface defects, mechanical and chemical bonding, increasing van der Waals forces and reactive groups, and diffusion.