Dual Cross-Linked Gelatin-Based Adhesive for Leather with Low Curing Temperature and Improved Bonding Strength

Gelatin-based adhesives have limited practical application due to their bonding strength and high curing temperature. In this paper, we prepared a dual cross-linked water-based adhesive from waste leather-extracted gelatin, dialdehyde-TOCNF, and polymethacrylate adhesive. The dialdehyde-TOCNF cross-linking with gelatin is accomplished through the Schiff base reaction, and poly-(methacrylic acid) was introduced to form hydrogen bonds with gelatin. The optimal bonding strength of the developed adhesive is achieved within a curing time of 40 min at a temperature of 50 C-degrees, which is lower than the shrinkage temperature of leather. The adhesive exhibited exceptional mechanical performance, with the T-peel strength and wet peel strength reaching 1081 and 400 N/m, respectively. The adhesive shows good bonding ability on hydrophilic substrates such as wood, and the dry and wet bonding strengths with wood were 5.52 MPa (57.72% higher than gel) and 4.71 MPa (1780% higher than gel), respectively. It highlights the versatility of adhesives in different materials.