Aging Effects on Paper Dispersibility – A Review

Abstract

The aging of paper significantly impacts fiber-water interactions, leading to a decline in dispersibility over time. This deterioration is particularly critical for water-dispersible paper and packaging applications designed to dissolve easily after use, as well as for recycling processes, where reduced dispersibility increases energy consumption and reject content. The aging process is notably faster and more pronounced in unbleached fibers compared to bleached fibers, indicating that lignin plays a crucial role in this phenomenon. A decrease in dispersibility is closely linked to reductions in water retention value (WRV) and increases in paper wet strength, driven by natural aging mechanisms such as hornification, auto-crosslinking, extractives self-sizing, and cellulose recrystallization. These processes reduce fiber swelling capacity and hinder paper disintegration in water. To mitigate the decline in dispersibility due to aging, minimizing moisture cycling and avoiding high temperatures are promising. Also reduction of refining energy and wet-end starch dosage in papermaking are ways to better preserve repulpability. Understanding these aging mechanisms is essential for optimizing paper formulations and ensuring long-term performance in both functional and recyclable paper products.