Main Article Content
Diethanolamine, epichlorohydrin (ECH), and lysine were used to change the traditional synthesis route to address the formaldehyde emission issue of melamine resin (MR), and a novel waterborne MR retanning agent with ultralow formaldehyde content (MUF) was finally obtained. The structure of MUF was characterized by Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance, and X-ray photoelectron spectroscopy, and its retanning performances in wet-blue and wet-white leathers were thoroughly investigated. Results showed that the formaldehyde content of MUF was 28.05 mg/kg, which was greatly lower than that of traditional MR (3550.23/2543.45 mg/kg), and the formaldehyde contents of chrome- and TWLZ-tanned leathers retanned by MUF were only 12.68 and 8.98 mg/kg, respectively. The thickening rates of MUF-retanned leather were up to 13.40% (chrome-tanned leather) and 9.58% (TWLZ-tanned leather), and MUF showed a satisfying overall performance in retanning leather. MUF is highly promising in practical application owing to its ultralow formaldehyde content, excellent stability in aqueous solution, and satisfactory retanning behaviors.