Effects of High-Consistency Pulping and Kneading on Recovery of Hydrophilicity and Strength of Recycled Paper Based on Fibers Hydrophobized by Gas Grafting with Palmitoyl Chloride

As environmental pollution problems arise due to the use of plastic, efforts are underway to replace it with ecofriendly materials. Gas grafting has ability to render cellulose surfaces hydrophobic, thereby imparting water resistance to paper. However, this hydrophobization poses challenges in recycling because disintegrating pulp fibers is difficult because of their poor wetting, and a reduction in hydroxyl groups adversely affects the absorbency and strength of recycled paper. In this study, we analyzed the effects of high-consistency pulping and kneading on the hydrophilicity and strength of recycled paper made from hydrophobized fiber through gas grafting with palmitoyl chloride. Experimental results indicate that high-consistency pulping was advantageous for recovering the hydrophilicity and strength of recycled paper based on hydrophobized fibers. During the kneading process, only hydrophilicity was recovered while the curling of fibers resulted in insufficient strength improvement.