Chemimechanical pulping of Eucalyptus grandis

AREA M.C.; GAVAZZO, G.B.; FELISSIA, F.E.; VALADE, J.L.

WOOD AND FIBER SCIENCE

Society of Wood Science and Technology

Año: 1995 vol. 27 p. 368 - 378

0735-6161

The genus Eucalyptus is currently one main fibrous raw material of the pulp and paper industry.The objective of the present paper is to optimize the Eucalyptus grandis chemimechanical pulping conditions, and to evaluate the obtained pulp quality to conclude on its use potential. Pulping raw materials were industrial Eucalyptus grandis chips from Celulosa Argentina´s mill, (Puerto Piray, Misiones, Argentina). The chemical stage was accomplished in a stainless steel digester with liquor´s recirculation system in all cases. The mechanical stage was carried out in an 8" atmospherical disk refiner. Sodium sulfite and sodium hydroxide were added as chemical reactives. The central composite experimental design used, involved 5 (five) levels of the two variables studied (2 factorial design + star + central point). Three (3) repetitions of the central point were accomplished for errors checking out. The studied variables were the initial amounts of sodium sulfite on wood (between 0.9 and 3.5 %o.d.wood), and reaction temperature (between 96 and 124. Times until temperature and at maximum temperature were 20 and 90 minutes, respectively. A constant sodium hydroxide level was maintained in all the experiences (1.5 %o.d.wood). Pulp evaluation was accomplished through usual characterization techniques. Chemical tests, and physical, mechanical and optical trials, were mostly done in accordance with TAPPI procedures. The obtained results show that the central point of the design used in this work (110 C and 2.5 % o.d.wood sulfite), seems to gather Eucalyptus grandis chemimechanical pulping best conditions of the studied variables. Obtained pulps could be used as furnish in printing and writing papers grades.