The low surface energy of plastics, including polyethylene and polypropylene, often has a negative impact on their printability. A non-soluble connection between inks and the plastic surface can only be achieved if both components have the same surface energy.
As inks, unlike plastics, have very high surface energy the plastic’s surface must be activated in order to equalise the two different energy levels. There are multiple ways to achieve this. With corona and plasma activation, for example, the substrate’s surface energy is increased using high-voltage discharge. High-voltage discharge in the air or in vacuo are currently the most advanced and successful surface activation methods available.
Corona and plasma treatment optimise the wettability of polymers. Their low surface energy has negative impact on the adhesion of inks, glue and other coatings on the substrate’s surface which, by nature, have very high surface energy. In order to ensure optimal wettability, the substrate’s energy level must be activated by applying high-voltage discharge in order for it to be equal or exceed the inks’ energy.
We offer corona and plasma surface treatment systems individually adapted to your direct printing solution.
Flame treatment activates the surface energy of glass and plastics and therefore improves the adhesion of liquids on the media’s surface. A gas flame, in our case a fuel gas blend with silane additive components, is used to increase the substrate’s energy level. Used on metals the ultra-thin silicate layer created by the silane components, protects the surface from diffusion of oxygen or humidity.
Ionisation neutralises static charges which sometimes occur on the media’s surface. This charge balancing prevents the risk of cloud formation around the motif and instead guarantees accurate and sharp contours. The ionization unit is, for example, integrated in our DP-UV flatbed printer models. Once set up, it automatically adjusts to the charge strength of every print run.