COLLOIDAL PROPERTIES OF HOLLOW LATICES AND THEIR ROLES IN CONTROLLING COLORIMETRIC PARAMETERS OF COATED PAPER SURFACE

With a view to seek the influence of hollow sphere pigments of latex upon the printed color on coated paper surface, the hollow sphere pigments were compared with filled ones in a variety of experimental approaches. Colloidal properties of latices were determined by measuring zeta potential and particle size distribution. For the amphoteric filled sphere pigment of latex, the polarity was reversed from the negative side to the positive side with decreasing pH. An extraordinarily high peak in the particle size distribution of the amphoteric filled evidenced aggregation between latex particles near the isoelectric point, depending on the electrolyte concentration and pH of the suspending medium. Coated papers containing the hollow sphere pigment in their coating improved optical properties like gloss and brightness. Optical parameters solely of the coating could account for this finding. An equation derived from the Kubelka-Munk equation calculated them fro twice measurements of reflectance of a coated paper over two substrates of different reflectances. This method permitted to predict brightness of coated paper of which coat weight would be different fro the actual one. The colorimetric parameters of solid-printed surfaces of the coated papers closely related to optical and structural properties of the coated papers. The color of the printed surfaces was dominated by the brightness and the smoothness of the coated papers. The hollow sphere pigments were proved to improve optical properties of coated paper and to control minutely colorimetric parameters of printed surfaces.