Use of esterases to improve the strength properties of mechanical pulp and to reduce refining energy.
Publication Date: 2002-Oct-08
The IP.com Prior Art Database
Several enzymes have been evaluated in the mechanical pulping processes to modify the fiber properties. Cellulases in general would reduce the strength properties. On the other hand, lipases can result in some improvement in strength due to the formation of fatty acid groups from pitch degradation. See, e.g., “Treatment of mechanical pulp and process waters with lipase”, Nordic Pulp and Paper Research Journal, 16(2): 125, 2001 It is known in the literature that alkali treatment of chips or fiber before refining can lead to dramatic improvement in strength properties, such as tear, tensile and burst. In the mean time, a decrease in refining energy was observed. Literature suggested that alkaline hydrolysis of ester bonds in lignin and carbohydrate increased the hydrophilicity of the fiber, which in turn improved fiber swelling and enhanced the strength properties of the paper. Sulfite treatment is also a common practice for the production of chem.-mechanical pulps. Sulfite treatment can also improve strength properties of mechanical pulp, because sulfonation of lignin could introduce considerable sulfonic acid groups on the pulp. It is evident that formation of acidic groups is the key to improve strength properties of mechanical pulp. The use of a non-specific esterase or combinations of several specific esterases for lignin, carbohydrate, pectins and extractives is designed to simulate the actions of alkali. Those esterases could degrade the ester bonds in the mechanical pulp material. The formation of carboxylic acid or hydroxyl groups on the fiber or the fines fraction should increase the swelling of the pulp and lead to better strength properties and reduced refining energy. In addition to lipases, improvements with in the strength properties have been obtained with cutinases. Cutinase treatment of a mechanical pulp led to about 20% increase in tensile strength and 5-10% increase in burst strength.