PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Because C-PAMs were used as dewatering agents at the Kleannara mill, CPAMs were selected as the retention aid in the white ledger line. However, a conventional C-PAM does not react well with increases in white ledger in the top ply line. Therefore, six types of C-PAMs were obtained from Songkang Industrial Co., Ltd. (Eumseongkoon, Korea), and their charge densities and molecular weights are shown in Fig. 1.
Fig. 1. C-PAMs as functions of molecular weight and charge density Methods Analysis of the properties of recycled pulp and virgin pulp
The pulp slurries were obtained from the machine chests of stock preparation lines. The initial consistencies of the pulp slurries were measured and diluted to 1.0% using tap water. The pulp properties, including freeness (TAPPI T227 om-09 2009), ash content (TAPPI T244 cm-99 1999), and fines content (TAPPI T261 cm-10 2010) were measured. The average fibre length was also measured using a fibre analyser (Kajaani FiberLabV.3, Metso, Finland). The handsheets were prepared from recycled pulp and virgin pulp. After handsheets with grammages of 100 ± 4g/m 2 were produced, the sheets were wet-pressed at 3.5kgf/cm 2 for 5 min using a laboratory wet press and dried at 120°C using a cylinder dryer. The dried handsheets were conditioned at 23°C and 50% relative humidity (RH) to control the moisture content of the handsheets at 8%. The physical properties of the handsheets were determined, which included bulk (TAPPI T411 om-10 2010), breaking length (TAPPI T494 om-06 2006), burst index (TAPPI T403 om-10 2010), and compressive strength (TAPPI T818 cm-07 2007). Measurement of the first-pass retention of white ledger stock First-pass retention was measured in terms of TAPPI T261 cm-10 (2010). The white ledger stock was diluted to 0.5% using tap water. Next, the C-PAMs were diluted to a concentration of 0.1% with distilled water. Then, 500 mL of the diluted white ledger stock was added into a dynamic drainage tester (Daeil Machinery, Daejeon, Korea) and stirred at a rate of 600 rpm for 30 sec. C-PAMs were added at the same mixing speed. The filtrate was collected from the stock after 90 sec. The filtrate was weighed, filtered, and dried at 105°C to achieve a stable weight. Equation 1 was used to calculate first-pass retention,
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Article 1 – Improving Retention and Strength
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