Thermomechanical Properties of the Polymer Binder Affecting the Processability, Structure and Properties of Dry Surface Treated Papers, 2003 Advanced Coating Fundamentals Symposium Proceedings

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The dry surface treatment (DST) method differs significantly from the conventional pigment-coating processes. The coating layer is applied to the substrate in the form of dry powdery particles and fixed on the surface with a thermomechanical treatment in a heated nip. In DST, the wetting of the base substrate is avoided, coating application is done without contact with the substrate and immediately to the required coat weight without any intensive coating penetration into the substrate.

In this paper we present the possibility to modify and control the structure and properties of the two-component (the coating system consists of pigments and a latex binder) dry surface treated papers. It was noted that processability in DST, as well as the properties of the coated paper, were significantly affected by the thermomechanical - the temperature dependent viscoelastic - properties of the latex binder. It appeared beneficial to have a high stiffness polymeric binder, particularly in the temperature region above its main (glass) transition, corresponding to a high gel content. This choice of binder decreased DST paper sticking to the heated roll during the fixation step of the coating and improved the surface strength of the final product.