The most common method to solve the adhesion of UV cured coatings for UV printers is to apply a layer of UV primer on the surface of the substrate. Due to environmental requirements, water-based base oil has become a natural choice.
Four Key Issues in Solving the Adhesion of UV Curing Coatings for UV Printers
The basic function of water-based UV primer is to ensure adhesion with the substrate and UV coating. When formulating, attention should be paid to the following factors:
1) The wettability of water-based UV primer on substrate: Due to the high surface tension of water, an appropriate amount of wetting agent should be added to the formula of water-based coatings to ensure that the primer evenly covers the substrate and reduces defects.
2) The adhesion of UV primer to substrate: In addition to the good wettability of the primer to the substrate, the adhesion to the substrate is mainly determined by the type of resin. When formulating, the molecular weight of the resin, glass transition temperature, and whether it contains polar groups (such as hydroxyl and amino groups) that can interact with the surface of the substrate should be considered.
Four Key Issues in Solving the Adhesion of UV Curing Coatings for UV Printers
3) The strength after UV primer curing: The strength requirements after primer curing come from the coating process on one hand, and on the other hand, it is necessary to ensure adhesion. This performance is mainly determined by the coating resin. In addition to resins, various fillers and additives in coatings also have a certain impact on strength.
4) The adhesion of UV primer to UV coatings and inks: This performance is the key to the success of the primer. On the one hand, a primer resin that is compatible with UV resin should be used to ensure affinity, and on the other hand, appropriate additives can be used to promote the penetration of UV resin in the primer layer.
