Pad printing is frequently used to print graphics on the exterior surfaces of minimally invasive medical devices. These graphics serve critical functions including product identification, location and orientation during surgical procedures. Strong adhesion of the ink to the device component is critical. Non-invasive vascular devices require integrity of the pad printed graphics for the proper identification and use of the device by clinicians. Invasive devices require that particles of ink are not released from the device into the bloodstream which can lead to serious side effects.
PEEK, thermoset polyimide and other chemically resistant polymers are increasingly being used for minimally invasive applications due to inherent strength and chemical resistance properties. These same material properties create greater challenges for pad printing.
Putnam Plastics’s plasma pre-treatment makes the outer surface temporarily receptive to chemical adhesion of the pad printing ink. Within a few days of being printed, the polymer surface recovers its chemical resistance for optimal performance in the field. While plasma pre-treatment increases ink adhesion on all plastics, it is of greatest value when used on polymers inherently resistant to thermal and chemical degradation such as PEEK and thermoset polyimide.
Putnam’s plasma technology uses advance equipment for sustained and computer controlled electrical discharge. The plasma reacts with the polymer surface of the component increasing the surface energy, which facilitates better wetting and bonding of the ink. Additionally the plasma oxidizes any organic surface contaminants that might interfere with the bonding of the ink to the component.
When compared to other methods of improving bonding, Putnam’s plasma pre-treatment involves little to no heat transfer into the polymer component, preserving its mechanical dimensions and properties. It involves no toxic chemicals, generates no toxic by-products, and reduces the need for toxic chemicals such as solvents in the ink, making it medically and environmentally friendly.