Evaluation of cellulase effect on the refining process of softwood bleached kraft pulp

As interest in the use of eco-friendly enzymes increases in the paper industry, an energy-intensive industry, the development of a wide range of enzyme application technologies is required. This study evaluated the effects of cellulase on the refining efficiency, fiber properties, and sheet strength of softwood bleached kraft pulp (Sw-BKP). The pulp was enzyme-dosed with cellulase for 6 h and refined using a laboratory beater for 15 min. The freeness and physical properties of the Sw-BKP fibers were analyzed. The pulp freeness decreased linearly as the refining time and enzyme dosage increased, indicating that the cellulase promotes refining efficiency by inducing fiber shortening and internal fibrillation during refining. Handsheets were prepared from 15-min refined enzyme-dosed and non-enzyme-dosed Sw-BKP. The strengths of the enzyme-dosed handsheets were lower than those of the non-enzyme-dosed handsheets because fiber shortening due to the cellulase activity was dominant during the refining. Therefore, cellulase effectively reduces refining energy consumption. However, it is essential to determine the correct enzyme dosage and refining time to balance the desired refining energy reduction with the resulting paper strength.