ABSTRACT
The purpose of this work was to analyze the characteristics of some eucalypts pulps available in the market, aiming to understand their influence in the properties of the offset papers. Another objective of this work was to show alternatives to reduce the number of laboratory tests in the pulp specifications. Thirteen (13) market pulps (Brazilian and international pulps) were analyzed and the tests applied were as follows: intrinsic viscosity, alkali solubility at 5%, coarseness, numbers of fibers per gram of pulp, average length of fibers, fine fraction by the Dynamic Paper Chemistry Jar (DPCJ), drainability by Schopper Riegler, before refining. Other tests, such as: tensile index, stretch, burst index, tear index, bulk, air resistance, opacity and absorption of water by cappilarity (Klemm) were performed for each type of pulp before refining and for refining levels of 25 ºSR, 30 ºSR, 40 ºSR and 55 ºSR. No evidence of the influence of S5 and intrinsic viscosity was observed at the range of the market pulp properties variation. The Brazilian pulps presented higher initial drainability and required lower PFI revolutions to the same level of refining in comparison to the international pulps. The initial average values of strength indexes: tensile, stretch, burst and tear were higher to the Brazilian pulps. However, this situation was changed at 25 ºSR and other levels of drainability. Due to the higher number of correlations at 30 ºSR, this level of drainability was chosen to determine the pulp characteristics profile. At this level, international pulps showed better values of tensile and tear index, but a higher energy consumption and a lower opacity in comparison to the Brazilian pulps. In addition, this paper suggested the concentration of the lab technical evaluation of pulps on the analysis of opacity, tensile and tear indexes. Such procedure should reduce the number of lab tests as well.
Key words:
eucalypt; offset papers; printing papers; pulps