Screen printing: Lack of ink adhesion

Ink applied to PVC films using the screen printing process does not adhere sufficiently to films from certain batches. It is known that adhesion problems of this kind can be caused by trace impurities on the polymer surface, so it is necessary to analyze the chemical composition of the outermost atomic or molecular layers of the film surface in order to find the exact cause of the differences in printability. The static SIMS method makes it possible to detect contamination of polymer surfaces or additives that have migrated to them with high sensitivity.

Pos. TOF-SIMS spectrum of a poorly printable PVC film (=> detection of lubricant additives)

Example: When analysing the surface composition of a poorly printable PVC film, the plasticizer dioctyl phthalate (® DOP), the PVC stabilizer barium stearate (® BS) and a lubricant additive called ethylene bis-stearamide (® EBS) are detected on the film surface.

Comparative measurements on easily printable PVC films show that these surfaces have significantly lower concentrations of the lubricant additive EBS. It was possible to prove that the poor printability of the films was directly caused by the increased concentration of the additive on the surface.