Características do papel reprográfico produzido com fibras de eucalipto e suas relações com a estabilidade dimensional

Abstract

Like any material made from wood fibers, paper also exhibits dimensional changes as a result of variations in moisture content. This property, called hygroexpansivity, is very important both in the papermaking and in the printing processes. The present work studies the hygroexpansivity of reprographic paper produced with eucalyptus kraft pulp, measuring this property during the process in an industrial paper machine. The study was developed using 75 g/m2 paper samples collected in different positions of a commercial paper machine running at a speed of 1256 m/min. Paper samples were collected along the paper machine, from the forming section up to the finishing section, and also along the cross machine direction at the reel. Besides hygroexpansivity, other physical properties of the paper samples were measured: grammmage, thickness, bulk, porosity, filler content, TSI (tensile stiffness index), TEA (tensile energy absorption), stretch, tensile index, tensile stiffness, breaking length, modulus of elasticity, tear strength and burst strength. The analysis of the results reveals the effect on hygroexpansivity of the operations and treatments involved in the papermaking process (formation, pressing, drying and finishing). The results are discussed with special emphasis on the correlations between hygroexpansivity and the other aforementioned properties.