A STUDY ON SURFACE AND BULK OF PAPER

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Results of coated paper-to-coated paper friction were summarized in the followings. Higher PCC ratio to clay in mixed pigment coatings resulted in higher static and kinetic COFs. Micro-roughness in the order of pigment particle size is considered to relate to it, as cube-shaped particles of PCC resist sliding. Calendering decreased COF at larger amounts of PCC, but did not change at all COF of the sole clay formulation. Addition of GCC decreased COF. The rate of decrease in kinetic COF with increasing the number of sliding for the GCC-rich formulation was higher than that for the PCC-rich formulation, presumably because protruding parts ; characteristic of the GCC-rich formulation, in the surface was selectively flattened. Addition of SB-latex up to 14 pph decreased COF, but static COF had the highest value at 18 pph. An anti-slip property as a rubber of SB-latex developed only in the static mode. Among lubricants used, the wax type decreased COF the most remarkably with more effects o … More n kinetic COF than on static COF.Results of exact porosity measurement and density measurement by the mercury buoyancy method were summarized in the followings. It was found that "mercury" thickness was lower than "micrometer" thickness for rough papers because mercury filled dents in surfaces, but for an A2 coat paper, the two of the thickness were very close. Porosity of coatings was found to decrease with increasing latex content. The degree of accuracy was approximately 1%. The porosity of coatings with carboxymethyl cellulose (CMC) was larger than that with polyvinyl alcohol (PVA).Results of effects of water-soluble polymers on SB-latex migration in the process of coated paper production were summarized in the followings. Cellulose derivatives like CMC, cellouronic acid, and hydroxyethyl cellulose suppressed latex migration. The reason is not ionic charge or viscosity, but linear chain structure of those polymers at a molecular level. It was predicted that they formed a loose network structure between pigment particles and trapped latex particles inside it. Less