Spraying cellulose nanofibrils for improvement of tensile and barrier properties of writing & printing (W&P) paper

Abstract

An experimental spray coater was used to coat writing and printing (W&P) paper substrate with cellulose nanofibrils (CNFs) suspensions. The effects of spraying variables (i.e. concentration of suspension, spray pressure, distance and time of spray) on the coated sheets were analyzed in terms of the tensile strength, water vapor transmission rate (WVTR), and oxygen transmission rate (OTR). Basis weight and the thickness of coated layers in the different treatments were measured. In addition, image analysis of the microstructure examined the coating adhesion. The WVTR of the papers decreased, while tensile strength increased with one layer of CNF coating. The OTR was not changed with the CNF coating. The tensile strength and microstructure images of the coated papers indicate good adhesion between the CNF coating and the paper substrate when using the spray coater.