Influência dos parâmetros de processamento em moinho de serras nas propriedades da celulose Fluff e de painéis absorventes.

Abstract

Fluff cellulose is a raw material applied in hygienic product production and its processing is performed via shredding mills to individualize the cellulosic fibers that comprise the absorbent core. The shredding process experiences operational machinery adjustments that have not been explored in terms of its impacts and potentials on the defibrated pulp and formed core properties. The objective of this study was to evaluate the impact of different processing conditions on the morphological and granulometric properties of shredded Fluff pulp as well as the mechanical strength of the absorbent cores produced from these pulps. The shredding process was developed using representative industrial scale parameters in a "sawmill" where different gap configurations, rotor speeds, and pulp feed streams were tested. The effects on morphological properties of fiber length, fiber wall thickness, and fines were investigated in addition to the effects on material granulometry, classified as Good Fluff, Nits & Knots, and Fines. The mechanical properties of tensile strength, tensile energy absorption (TEA), and absorbent panel elongation were evaluated and the results statistically correlated with previously evaluated properties. The Fluff pulps used in the experiment are from conifers with similar specifications, varying mostly in moisture content. The results demonstrate that the reduction in fiber length and wall thickness were influenced only by the use of narrow gaps between knife and counter-knife. The higher total fines content, in particular Fines A were influenced by the increase in the feed stream and Fines B by the use of a wider gap and higher pulp moisture. In the granulometric analysis, there was a significant improvement in the shredding uniformity obtained through higher Good Fluff contents and reduction of Nits & Knots when lower feed streams, higher rotor speeds, narrowed gap, and lower pulp moisture were used. The granulometric fines content was impacted only by the use of narrowed gaps. Furthermore, for the conditions of this study, no correlation was obtained between morphological and granulometric fines. The properties of tensile strength, TEA, and elongation were superior using the Fluff pulp with the highest humidity and which presented the highest Nits & Knots content, in addition to being positively influenced by the higher Fines B content. This study proves that depending on the productive bottleneck and the particularity of each absorbent product manufacturer, the optimization of the mill parameters together demonstrates relevant gains in terms of shredding uniformity, product strength, and process savings linked to improved performance of the Fluff pulp used.