Measurement of the surface tension
The adhesion of a surface is usually directly dependent on the surface energy. If the surface energy is substantially lower than that of the printing ink used, the wetting is disturbed, resulting in poor adhesion.
For this reason, plastic surfaces have to be pre-treated. Depending on the type of ink used the surface tension required can vary:
- solvent based inks => 38 bis 42 mN/m (=Dyn/cm)
- water soluble inks => 40 bis 44 mN/m
- UV inks => 44 bis 46 mN/m
With the test inks of AFS, which are available from 34 to 56 dyn/cm surface tensions of plastic films can be easily and reproducibly determined according to DIN ISO 8296. Depending on whether the ink sticks or bubbles on the surface it indicated whether the surface tension is above or below the dyne-value of the currently used test ink.
We also offer the test inks in a case with 12 bottles from 34 to 56 dyn/cm.