Abstract:

　In recent years, the transfer quantity of dumping water onto the newsprint in offset printing has been increasing. This is due to the popularization of four-color printing. In order to achieve the desirable four-color offset printing property, the role of sizing the newsprint has become increasingly important. The trend of high loading of recycled pulp and of high machine speed causes a pitch trouble. The solution is to change the sizing method from internally to surface application.
　The purpose of this study is to propose the optimal surface size solution for four-color offset printing, and to clarify this mechanism. The sizing performance of various surface size with different chemical structure was examined. Dispersive and polar components of surface free energy were measured by a dynamic adsorption tester (DAT). The dynamic fiber expansion with wetting was analyzed using dynamic penetration measurement (DPM).