EFFECT OF FIBRILLATION ON THE ABILITY OF CELLULOSE FIBERS TO SUPPRESS THE AGGREGATION OF QUINACRIDONE

Abstract

Quinacridone is a red–violet pigment often used as a coloring agent. However, the aggregation of quinacridone needs to be resolved to avoid undesirable color changes. Cellulose nanofibers are a potential candidate for novel pigment dispersants, due to their ability to inhibit aggregation. In this study, the effect of the degree of fibrillation of cellulose fibers on their performance as dispersants was investigated. Four types of highly fibrillated cellulose particles (HFCPs) were prepared using a disk mill and a high-pressure homogenizer. The degree of fibrillation was evaluated using specific surface area measurements, scanning electron microscopy, and gravitational sedimentation analysis. Fibrillation of cellulose was found to increase its adsorption capacity toward quinacridone. Even partly fibrillated celluloses successfully inhibited the aggregation of quinacridone. Color measurements of the quinacridone–cellulose suspensions indicated that, although fibrillation of cellulose improves the chroma of the suspensions, excess fibrillation causes a decrease in the chroma.