In order to protect the headlamps from stone-chipping, polycarbonate (PC, PMMA) headlight lenses need to have high surface hardness. For this reason, headlamp surfaces are usually coated with a scratch-proof, UV-cured paint (often using an acrylic polymer). These protective scratch-proof coatings offer up to 40 times more resistance against physical impact compared with uncoated lenses.
The use of Openair® Plasma rotary jets enables efficient and gentle microcleaning of polycarbonate headlight covers prior to coating them with paint finishes.
Plasma cleaning removes particles (dust, pigments, etc.) still adhering to the surface after the injection molding process. At the same time, it ensures that the lens is electrostatically discharged. Anti-static blowers are no longer required.
The specific and uniform surface tension achieved results in optimal distribution and uniform thickness of the subsequently applied coating layer. Openair® Plasma thus significantly decreases reject rates.
As an alternative to hard-coat painting, scratch-proof and long-term plasma coatings can be applied on the lenses. Applying these coatings using low-pressure plasma (i.e., a chamber plasma process) provides added durability to these hard surface coatings on polycarbonate. The low-pressure plasma causes functional chemical groups to become embedded into the surface, resulting in a more highly crosslinked coating. The Plasmatreat low-pressure plasma treatment can improve surface hardness by as much as a factor of 100X for some popular materials.
POLYMER COMPOSITES 2019
ADHESION Adhesives & Sealants (4/2018)