Characterization of the Paper Coating Structure Using Focused Ion Beam and Field-Emission Scanning Electron Microscopy. 2. Structural Variation Depending on the Glass Transition Temperature of an S/B Latex

The glass transition temperature (T g) of an S/B latex binder, which is highly related to the film-forming properties of latex, has long been of interest, and its effects on the properties of the coating layer are well-known. Measurements of the bulk and surface properties of coating layers or the properties of coated papers have been used to investigate the effect of T g on the coating structure. However, these approaches cannot provide a detailed analysis of the coating structure because they give an average value for the whole coating layer. We applied a newly developed image analysis method, consisting of smart blur and locally adaptive thresholding techniques, for evaluation of the coating structure depending on the T g of the S/B latex and the calendering conditions. This approach allowed us to obtain the average pore structure, pore shape, pore size, and Z-directional distribution. The changes in the coated paper properties by calendering or latex types were compared and analyzed based on the coating layer structure.