High quality UV digital printing on various materials with plasma enhanced surface
| Authors | |
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| Year of publication | 2022 |
| Type | Conference abstract |
| MU Faculty or unit | |
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| Description | The UV digital printing technology is widely used for high variety of surfaces. However, the ink composition, UV light intensity and surface chemistry must be perfectly tailored for the printed layer to adhere to the desired material. An industrially proven process for tailoring of surface chemistry of the printed material often uses aggressive chemicals (socalled primers). This process is cumbersome with limited use for larger surfaces since the application of the primer is done by hand. During our cooperation with UV digital printer manufacturer, we have been able to prove that plasma modification of the surfaces can yield adhesion improvements satisfactory for industrial standards even without introducing any other chemical into the mix. Plasma discharge used for the treatment of polycarbonate, polymethyl methacrylate, and acrylate layer on top of aluminium plate was our Diffuse Coplanar Surface Barrier Discharge and its novel modification suitable for printer implementation. Every material has been evaluated by various measurement methods from which the free surface energy measurement, peel test (adhesion), and crosscut test (industrial adhesion test) were performed in most detail. For all materials, the surface energy and peel test adhesion values rose with a higher exposure time. However, for industrial partners, the most critical test is the crosscut adhesion test according to the prescribed ISO norm. For this evaluation method, we have discovered significant differences for each material that lead to development of the treatment process with separate parameter adjustments from the printing head – so the printing will not be slowed down by plasma treatment. For example, results on the acrylate layer on top of aluminium showed the best adhesion improvement for short exposure times (1-3s) and worsening of the adhesion for any exposure time over 5s, which is in sharp contrast to polymethyl methacrylate surface that needed exposer times in an interval of 60s to properly improve adhesion. This and all other results are presented at the poster presentation. |
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