Effect of pulper consistency on stickies size distribution

Pulper consistency affects production capacity, defibering efficiency, and particle size distribution of contaminants, and in particular, stickies and inks. The effect of pulper consistency on stickies size distribution, though important, has not been studied in detail. In this project, pressure-sensitive adhesive (PSA)-containing furnish was pulped in a laboratory at 5%, 10% and 15% consistency. Results show that 15% consistency pulp produced many more small-sized stickies compared to pulps produced at 5% and 10% consistency. This is contrary to the generally accepted hypothesis and needs further investigation. Calcium carbonate, usually present in varying proportions in many recovered paper grades, is known to have some pacifying effect on stickies. A new pacifying agent prepared from silicone release liner, called desiliconized pulp (DSP), behaves like bleached virgin hardwood kraft pulp. DSP seems to have a pacifying effect similar to that of calcium carbonate. Thus, DSP may potentially replace a small amount of bleached virgin hardwood kraft pulp, with a bonus stickies-pacifying effect.