ABSTRACT:We studied the surfaces, including both the composition effects and the processing rates, of polypropylene (PP) composite films used for synthetic paper to determine the surface free energy (␥ s ) and the irregularities on the film surfaces. We correlated these two characteristics to the printing quality by assessing the facility with which the offset ink was removed from the surface of the paper and also the ink absorption. Five films with different compositions were uniaxially oriented with a flat-die extruder at two different stretching rates. The results of scanning electron microscopy (SEM) of the films showed good dispersion and distribution of the filler particles used in the compositions of the films and also of the polystyrene (PS) dispersed throughout the PP matrix. The SEM analysis also revealed slightly high surface irregularities on the film surfaces through a high concentration of CaCO 3 , which thus increased the coefficients of static and kinetic friction and the ␥ s values. These film properties created better printing quality and also more strongly fixed offset ink onto the film. However, the films with high relative quantities of PS in their composition showed a high polar component in their total ␥ s when compared to films with less PS or no PS in their compositions. However, because of the apolar characteristic of the offset printing ink, the ink absorption worsened. The films underwent stretching at two different rates, which did not significantly affect the ␥ s values or the friction coefficients; however, they did slightly change the printing quality and ink adhesion.