Improving Brightness Stability of Mechanical Papers - Application of Yellowing Inhibitors with a Mini Pilot Film Coater, 2002 Coating Conference Proceedings

Z. Yuan, J. Schmidt, C. Heitner and M. Fairbank

A pilot film coater was used to evaluate the effect of yellowing inhibitors on brightness stability, physical properties, and printability of a coated high-brightness paper made from 100% bleached thermomechanical pulp (BTMP). Incorporating a hydroxyphenyl benzotriazole ultra-violet absorber and a hindered hydroxylamine radical scavenger into a pigment coating formulation significantly improved the light stability of the BTMP paper. The pigment coating alone increased the stability of the base paper somewhat, with its effect depending on the coat weight applied. The inhibitors were compatible with the coating formulation and caused no runnability problems. Samples prepared using a laboratory film applicator had a similar light stability to those prepared with the pilot system. Generally, the yellowing inhibitors had a negligible effect on the physical properties and printability of the treated paper.