Alkaline treatment and fractionation of OCC for strength improvement

Abstract

The main drawback of recycled fibers is the deterioration of fiber bonding dependent papermaking properties (like tensile, tear and burst indexes) due to the hornification effect, as a results of drying during papermaking. In order to improve the papermaking properties through increasing fiber bonding, an alkaline treatment of Old Corrugated Cardboard (OCC) followed by fractionation were carried out in this investigation. Alkaline treatment dissolved 6.6 % organics (carbohydrates and lignin) and fibers became wider as a results of fiber swelling. The alkali treatment decreased fines from 39.9 % to 28.5 %, consequently, decreased drainage resistance from 26 °SR to 21 °SR. The papermaking properties of OCC pulp increased on alkaline treatment. Fiber fractionation of alkaline treated OCC further increased papermaking properties. At 40 °SR value, the tensile index, burst index and tear index of alkaline treated longer fiber fraction was 49 N m/g, 3.2 kPa m2/g, 7.2 mN m2/g, respectively while it was 40.4 N m/g, 2.1 kPa m2/g and 6.1 kPa m2/g, for non-treated longer fiber fraction, respectively.