Polymer and paper structures have been successfully utilized in several fields, especially in the packaging industry. Together with barrier properties, printability is an important property in packaging applications. From the point of view of printing, the dense and impervious structure of extrusion coatings is challenging. Flame, corona and atmospheric plasma treatments were used to modify the surface of low density polyethylene (LDPE) and polypropylene (PP) and the influence of these surface modifications on print quality, i.e., toner adhesion and visual quality was studied. The traditional surface treatment methods, i.e., flame and corona treatments, increased the surface energy by introducing oxygen containing functional groups on the surfaces of LDPE and PP more than helium and argon plasma treatments. Only in the case of flame treatment, the higher surface energy and oxidation level led to better print quality, i.e., toner adhesion and visual quality, than the plasma treatments. The morphological changes observed on LDPE surface after flame treatment are partly responsible for the improved print quality. Atmospheric plasma treatments improved the print quality of LDPE and PP surfaces more than corona treatment. The electret phenomenon observed on LDPE and PP surfaces only after corona treatment is the most likely reason for the high print mottling and low visual quality of corona treated surface.

Plasma deposition equipment was developed and installed at a pilot extrusion coating line for reel-to-reel substrates. Hexamethyldisiloxane was used as a siloxane precursor for the atmospheric plasma deposition of siloxane coatings on substrates of three different categories: paper, polyethylene-coated paper, and textile materials (woven cotton fabric and polypropylene nonwoven). SEM, H 2 O contact angle measurements, heat sealability, and water vapor barrier measurements were carried out to characterize the composition and surface structure of the samples. The potential of the method and the equipment was shown by the coatings, ranging to micrometer scale. With selected samples, hydrophobic coating was shown to form at speeds up to 100 m/min.

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