内添による紙の機能性発現機構について

Abstract

Wet-end additives can give new functionalities to papersheet efficiently in the papermaking process. The additives have various forms ; molecular-order compounds, emulsions, their coagulants and others. The appearance of functionalities on papersheet is also various, depending on the way to coagulate the wet-end additives and/or that to adsorb the coagulated compounds on pulp fiber surfaces in wet-end. The research fields of wet-end additives have remarkably advanced, as the new methods for determining wet-end additives in papersheet have been established recently, such as pyrolysis-gas chromatography and SEM-EDXA.In the case of reactive sizes such as AKD and ASA, the chemical structures to react with water is necessary for efficient sizing of papersheet. Surface charges of the emulsion particles of the reactive sizes turn from cationic to amphoteric in wet-end, and thus efficient retention of the reactive sizes can be achieved. Furthermore, lower coagulation behavior of size components on pulp fiber surfaces is maintained by the water-reactivity of reactive sizes in press and drying processes, and sizing features appears efficiently on papersheet thereby.Sizing and retention mechanisms of rosin soap, rosin emulsion and rosin-ester sizes also have been studied using new analytical techniques, from the aspects of structures of rosin molecules in papersheet and roles of alum in wet-end and in papersheet.