Developing Waste Fatty Acid-Grafted-Silicone Oil as Repulpable, Enhanced Gas- and Water-Resistant Coating for the Paper Industry

Developing a simple and low-cost approach to produce paper coatings with repulpability, water resistance, and barrier properties remains a challenge. Herein, waste monomer fatty acid-grafted silicone oil (WMASO) was developed as an efficient coating for paper substance through a simple ring-opening reaction of waste monomer fatty acids from the dimer acid industry with epoxy silicone oil. Due to the formation of dense coating and the synergistic effects of long-chain alkyl groups with repeated Si–O segments, the WMASO exhibited excellent water resistance and barrier as well as mechanical properties. When the paper was covered with 25 wt % of WMASO and 75 wt % of oxidized starch (OS), the waterproof, water vapor barrier, and tensile properties of coated paper (OS&1/4WMASO-p) were superior to those of paper coated by traditional oxidized starch (OS-p). Specifically, compared with OS-p, the Cobb 60 and water vapor transmission rate of OS&1/4WMASO-p, respectively, decreased by 58% and 74%, whereas the folding property of OS&1/4WMASO-p increased by 62%. Importantly, the mechanical properties of repulped OS&1/4WMASO-p were similar to those of uncoated paper, implying that the coated paper covered with OS&1/4WMASO has excellent repulpability. This study provides a facile and industrially feasible strategy for the large-scale production of biobased, waterproof, barrier, and repulpbale coating for paper-derived packaging.