Effects of hydroxyethyl methacrylate comonomer in styrene/acrylate latex on coating structure and printability

The quality of coated paper, including its appearance and printing properties, is closely related to the structure of its coating layer, which is affected by components such as the pigment and binder. The binder, in particular, contributes to the structural formation and maintenance of the whole framework of the coating layer. Hydroxyethyl methacrylate (HEMA) is a hydrophilic monomer that is used as a functional monomer for the emulsion polymerization of styrene-acrylate (S/A) latex. In this study, the effects of HEMA in S/A latex on the properties of coated paper were investigated. The paper coated with an S/A-latex containing HEMA monomer was found to have a rougher and less glossy surface, but its printing qualities, i.e., print gloss, pick resistance, and print uniformity, were significantly improved. S/A latexes that contain HEMA as a comonomer were found to be more uniformly distributed over the coating surface and in the thickness direction. The uniform distribution of HEMA latexes in the z-direction was confirmed using a fluorescence-tagged latex binder and confocal laser scanning microscopy. The changes in the paper properties with respect to the HEMA content in the S/A latex were investigated and improvement in the printing properties was observed.