Produção de papel kraft com fibra reciclada e celulose microcristalina

Abstract

Packaging is largely produced from plant origin cellulose and is characterized as short fiber (SF) when the cellulose comes from Eucalyptus spp., and long fiber (LF), when it comes from Pinus spp. The development of e-commerce has increased the consumption of packaging. In 2021 there was economic growth in the Brazilian packaging industry of 31.1% compared to 2020. Nevertheless, the planted areas of Pinus spp. show a trend of imbalance between supply and demand in Brazil. In order to meet market demand, make up for the lack of vegetable raw materials and produce Kraft paper in a way that has less impact on the environment, many companies are increasing their use of recycled fiber. However, its inclusion in the recipe can directly influence the quality of the product, especially its strength. A promising alternative for forming paper with a stronger and more resistant fibrous network is to use cellulose on a micro-scale. In order to assess the influence of using recycled fibers on the quality of Kraft paper, the first stage of this study consisted of producing bench-scale samples of Kraft paper with different percentages of virgin fiber (SF and LF) and recycled fiber (RF), and characterized it physically using grammage, moisture content, Gurley porosity, Z-traction, SCT and Mullen analyses. The second stage of this study consisted of reproducing the first stage by including microcrystalline cellulose (MCC) and eliminating the use of LF. The tests were repeated for three refining ranges. The study was carried out in an industry in southern Brazil that uses the Kraft production system. The percentages of compliance with the quality specifications of 120 g.m-2 paper from the company where this study was carried out were approximately 100 % for humidity, 11 % for porosity, 94 % for Z-traction, 83 % for SCT and 100 % for Mullen. For the tensile, compression and burst index, it was observed in the: 1st Test (MCC = 0 %) that the higher the percentage of recycled fiber, the lower the paper strength, however, the results were better for refining range R1 (Freeness 300 - 350 mL); 2nd Test for Formulation 3 (MCC = 6 %) higher strengths than in Formulation 2 (LF = 0 %). On average, the increase in traction index was 10.5% for all refining ranges for F3 compared to F2. This study shows that the addition of up to 6 % MCC strengthens recycled fibers and reduces dependence on Pinus spp. providing the production of more sustainable and resistant packaging.