Cellulase-assisted refining of bleached softwood kraft pulp for making water vapor barrier and grease-resistant paper

Abstract

The effect of cellulase pretreatment of bleached softwood kraft fiber before laboratory refining on the water vapor barrier and grease resistance properties of handsheets was investigated in this work. In contrast to no cellulase pretreatment, cellulase pretreatment at 0.5 filter paper units (FPU) combined with refining for 7500 revolutions was effective in reducing the water vapor transmission rate (WVTR, 50 % RH and 23 °C) of the paper by 83 % and achieving 100 % grease resistance over a 24-h test period. After cellulase pretreatment, the fiber morphology and hydrophobicity changed dramatically as a function of refining intensity. The role of cellulase pretreatment in reducing the WVTR and grease-stained areas was revealed on morphological observation by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, as well as water contact angle testing.