1. Preparation treatments

The purpose of this operation is to facilitate the adhesion of paints, varnishes or inks to certain plastic substrates with low surface tension, so as to create roughness or polar groups for good adhesion. This is particularly the case with polyolefins (PE, PP).

The substrate's ability to be wetted by the deposited coating is essential for adhesion. Like paper, polymers can be decorated or printed using common or similar techniques, albeit with specific dyes or inks.

As a general rule, plastics that bond well are easy to decorate or print, and vice versa (see table 1 ).