Fully Biobased Cardanol-Grafting-Dimer Acid Glycidyl Ether as Repulpable and Multiple Resistance Coating for Paper

Abstract

Designing a feasible and low-cost strategy for manufacturing repulpable and fully biobased coating for paper substance with excellent water- and oil-resistant and gas barrier properties remains a challenge. Herein, a fully biobased cardanol-grafting dimer acid diglycidyl ester (CGDAE) coating for paper substance was fabricated through the ethoxylation of dimer acid (DA) and then addition with cardanol under solvent-free conditions. The results indicated that the packaging performance of the paper substance was significantly improved after coating with the mixture of resulting CGDAE and oxidized starch (OS); among them, the paper covered with 80 wt % of CGDAE and 20 wt % OS (80% CGDAE/OS-p) exhibited excellent water resistance (water contact angle of 110.3°) and oil repellency (kit rating 11/12), which were increased 2.9 and 3.7 times compared with those of paper substance coated by traditional OS (OS-P). Compared with those of paper coated by OS (OS-p), benefiting from the formation of dense coating and the hydrophobic long-chain alkyl groups, the water vapor transmission rate and oxygen permeability of 80%CGDAE/OS-p decreased by 57.8% and 96.5%, respectively, and the freshness lifetime of strawberries packaged with coated paper was increased from 4 days (OS-p) to 7 days (80%CGDAE/OS-p). The pulp repulpability of 80%CGDAE/OS-p was confirmed by washing and a repulping treatment. This study presents a cost-efficient and industrial strategy for fabricating fully biobased, recyclable, and water- and oil-resistant coatings for paper-derived packaging.