Influence of modified starch polymers on paper printability

Non-ionic and anionic modified starch polymers with various functional groups and degree of substitution were synthesised in order to evaluate the influence of decreased hydrophilicity. In this study, emphasis was on the low or moderate degree of substitutions of selected substituents in order to keep modifications as simple as possible. Lower degree of substitution requires also less reagents and that way it is more cost efficient compared to highly substituted starches. Solubility and viscosity of aqueous solution or dispersions/dilute gels varies with varying substituent, degree of substitution and molecular weight. This influences to selection of coating technique when applying starch polymer on paper surface. Significant changes in paper surface chemistry as well as in imprint quality were received with low polymer amount on paper surface. Suitable technique for coating paper with low amount of modified starches in pilot scale was tested. In order to influence offset printability with low polymer treatment, the porosity of used base papers with no mineral coating was too high. Ink setting property of mineral pre-coated paper grade could be modified with low polymer treatment. Good printing results were received when adjusting paper gravure and inkjet printability with low amount of chemically modified starches.