915 WOOD RESEARCH 61 (6): 2016 915-926 INFLUENCE OF THE COATING FORMULATIONS AND BASE PAPERS ON INKJET PRINTABILITY Juraj Gigac, Monika Stankovská, Andrej Pažitný Pulp and Paper Research Institute Bratislava, Slovak Republic (Received July 2016) ABSTRACT At the coating were used two substrates, commercial base paper and base paper produced in pilot experimental paper machine. The printing quality varied at both base papers. The coating colours contain commercial silica and precipitated calcium carbonate pigments. As a binder was used polyvinyl alcohol and cationic starch combined with high-cationic polymer SMAI 1000. Colour gamut significantly improved when the inkjet ink contact angle decreased below 14° independently of the base paper. The order of coating colours effect on the base papers was similar. Application of silica pigment in the coating colour provided papers with the largest inkjet ink wetting, the best colour gamut area, print sharpness and smoothness. By using of polyvinyl alcohol, a high colour gamut area was reached but it resulted in a markedly low print sharpness in comparison with cationic starch. Coating of base paper produced in pilot experimental paper machine introduces papers with higher colour gamut and also print sharpness. KEYWORDS: Inkjet printing, base paper type, coating colour, pigments, binders, printing properties, wettability. INTRODUCTION At present time there is an increasing demand concerning the printing quality of printing paper grades. Inkjet quality depends on interaction between ink and the receptive surface. Inkjet print quality can be regarded in a variety of ways, mainly colour reproduction and print sharpness. A coating layer covers base paper fibres to give a uniform surface. It is desirable during printing process that water part of ink absorbs rapidly into the porous structure of paper and dye anchors on the surface layer. It was found that coating with pores up to 0.1 μm absorbs dyes slowly, whereas pores within range 0.1-1.0 μm can cause absorption of the part of dye below coating surface and this may result in a decrease of optical density (Morea-Swift and Jones 2000). A thorough review of absorption of ink into paper as well as the experimental study of connection between various coated surface properties and print quality properties had been published by authors