Kraft Pulp Yields and Paper Properties of Ten-year-old Clonal Acacia hybrid (<i>Acacia mangium × Acacia auriculiformis</i>) Wood

Clonal Acacia hybrid ( Acacia mangium × Acacia auriculiformis ) breeding in Indonesia aims to improve wood quality for the paper industry. This study investigated the effect of anthraquinone (AQ) addition on the quality of pulp and paper from ten-year-old clonal Acacia hybrid (015D) wood. Pulp making was carried out by kraft process with an active alkali concentration of 17%, sulfidity of 25%, and AQ concentrations of 0%, 0.05%, and 0.10% at a maximum temperature of 170oC for two hours of cooking time. AQ addition increased the yield to 54.70%, 58.23%, and 59.14% and decreased the kappa number to 24.06, 20.30, and 16.87, respectively. In terms of physical and optical properties, the paper had a burst index ranging from 3.31 to 3.66 kPa·m 2 /g, a tear index ranging from 1.72 to 2.40 mN·m 2 /g, a tensile index ranging from 49.41 to 50.28 Nm/g, opacity ranging from 87.38% to 88.44%, and brightness degrees ranging from 24.18 to 25.78. Burst and tensile indices met the Indonesian National Standard for broadleaf wood. AQ at 0.05% to 0.10% significantly reduced kappa numbers but did not significantly affect yield, mechanical, or optical properties. Therefore, an AQ concentration of 0.05% is recommended for clonal Acacia hybrid wood