Comparative Investigation on Different Methods for Improving Strength Properties of OCC Pulp

The pulp strength properties of old corrugated containers (OCC) are reduced as a result of recycling process. So at present paper, improvement of OCC pulp properties was investigated through refining and also using cationic starch and imported unbleached softwood kraft pulp (USKP). In addition to studying the effects of each of above mentioned parameters, the effects of combined treatment of refining + cationic starch, refining + USKP, and cationic starch + USKP were also investigated. Cationic starch at 3 dosing levels (0.5, 1.0 and 1.5%) and USKP at 3 dosing levels (5, 10 and 15%) were used in admixture with refined and unrefined OCC pulps. The results have shown that treatments such as refining, cationic starch, USKP, and cationic starch + USKP significantly improved the OCC strength properties. The highest strengths were obtained from treatment of 1% cationic starch + 15% USKP, which in comparison with reference sample; about 40% increase in burst and tensile strength, and 30% increase in tear strength were occurred. Air resistant, in treatment where 1.5% cationic starch was used in refined pulp, was increased 45% as compared with the reference sample. The results showed that the optimum treatment, in terms of obtaining highest improvement in OCC pulp properties, was a combined treatment of refining + cationic starch + USKP. However, depending on the required end use quality, OCC pulp can be improved by using refining treatment with or without using different dosages of cationic starch and USKP.