INFLUENCE OF THE INTERACTION ZONE BETWEEN COATING AND PAPER ON THE DYNAMIC-MECHANICAL PROPERTIES OF A COATED PAPER

Papers coated with pigments bonded by polymer latexes have been tested by dynamic mechanical analysis. Measurements in tension and in three-point bending have been performed to determine the influence of the interaction zone between the coating and the paper on the properties of the coated paper. Comparisons have also been made with results from measurements in torsion. Experimental values of Young's modulus and the peak height of tan delta were higher than values theoretically calculated from data obtained on the separate layers, the paper and the coating. This deviation is interpreted as being due to the influence of an interaction zone between the coating and the base paper. if the thickness of the interaction zone is taken into account in the theoretical model, a better correlation with the experimental values is obtained for the peak height of tan delta. Higher values of the experimental data for the shear modulus of coated paper than from a weight-average calculation of the shear modulus of the pure components were obtained. This can be explained as being due to an increased stiffness of the coated paper as a result of the interaction zone, that was not adjusted for in the model. Further evidence for the existence of the interaction zone was provided by the pigment and latex distributions in the cross-section of coated papers determined in a scanning electron microscope using energy dispersive X-ray analysis.