Thermo-mechanical Pulps from Tropical Pines

Pinus greggil, Pinus pseudostrobus, Pinus montezumae and Pinus taeda chips were pulped by thermo-mechancial pulping process to produce pulps suitable for newsprint production. In all the cases the chips were subjected to about 125°C temparature for a period of 3 minutes and refined. In first stage refining a plate clearance of 3.0 mm was kept and refining was done at 17 ± 2% consistency. The pulps were refined in second stage at a plate clearance of 0.15 mm to obtain a freeness of 250 ± 20 ml C.S.F. All the four species of tropical pines produced pulps having satisfactory strength properties. The standard hand sheet properties. In all the cases were almost similar (tear index 2.27 ± 0.2, tensile index 8.5 ± 1.3, opacity 99 ± 0.5 and brightness of unbleached pulps 35.5 ± 1.6% I.S.0.). The results indicated that pulps, in ultra high yield could be prepared, suitable for newsprint production from these tropical pines. The unbleached pulp brightness was, however, lower which could be increased by employing a lignin preserving bleaching method.