Research of polypropylene (PP) decorative board surface painting used for wood product decoration and the paint film adhesion improvement by plasma

This study is to analyze influences of plasma treatment on waterborne painting film's adhesion by testing a sample made of polypropylene (PP) decorative board, the substrate, processed with low temperature plasma PP surface treatment, and coated with waterborne primer coating and topcoat paint. A contact angle goniometer was used to characterize influences of plasma modification on the surface wettability of PP decorative board; an Atomic Force Microscope (AFM) was used to detect changes on surface features of the PP decorative board before and after plasma treatment; an X-ray photoelectron spectrometer, XPS, was used to test changes in chemically active elements on surface of the decorative board before and after plasma treatment; a cross-cut tester was used to test waterborne paint film's adhesion before and after plasma treatment, with the aim to explore the performance and mechanism of plasma treatment to improve the adhesion of waterborne paint film on the PP decorative board surface. The results indicated that plasma treatment can significantly reduce water contact angle on a PP decorative board material's surface and increase its surface free energy and roughness. Furthermore, plasma modification can form on the surface of the PP decorative material a large number of oxygen-containing active elements which is beneficial to spreading, adsorption and adhesion of waterborne paints on the material surface. Therefore, plasma modification can improve adhesion of waterborne paint films on surface of PP decorative board, to Grade 0-1, so can widen the applications of PP decorative board on surfaces of wooden products.