Effect of the glass-transition temperature of latexes on drying-stress development of latex films and inkjet coating layers

Abstract

Highly porous silica pigments and PVOH binder are commonly used for inkjet coated papers. The use of PVOH increases the viscosity of coating colours and increases drying stresses in the coatings. In this study, the possibility of using S/A lattices as inkjet binders to decrease the viscosity of inkjet coatings and meet the quality requirements of the inkjet papers was investigated. Three S/A latices were prepared and tested as binders for inkjet coating. The effect of drying temperature and binder T g on the drying stress development and crack formation in the coating was investigated. The results showed that the T g of S/A latices, drying temperature, and PVC influenced the drying-stress patterns during drying. Drying stress decreased as the T g of the latex decreased and the drying temperature increased. The presence of silica pigment caused a sudden increase and then decrease of the drying stress due to cracking of the coating layer. Two S/A latices gave coating colours with lower Brookfield viscosities and drying stresses than conventional PVAc latex, and they also gave coatings similar in brightness, opacity, gloss and roughness to the conventional latex coating.