Kraft Pulp Yields and Paper Properties of Ten-year-old Clonal Acacia hybrid (Acacia mangium × Acacia auriculiformis) 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·m2/g, a tear index ranging from 1.72 to 2.40 mN·m2/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