A novel approach for preparing aldehyde-free melamine resin and investigation of its retanning performance

Melamine resin (MR), traditionally synthesized using melamine and formaldehyde, is widely used in the leather industry. However, the emission of free formaldehyde poses a significant challenge for conventional MR. To address the issues of aldehyde in MR, extensive research has been conducted. This paper introduces a novel aldehyde-free MR (LTSL) retanning agent synthesized using cyanuric chloride, l-lysine, and sodium sulfanilate. The chemical structure of LTSL was analyzed via Fourier transform infrared spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The presence of amino, carboxyl, and sulfonic acid groups in LTSL enhanced its storability and imparted LTSL with an amphoteric character. The isoelectric point of LTSL was optimized to reach 4.37, and LTSL exhibited an appropriate size distribution with an average particle size of 254.17 nm and achieved high absorption rates of 87.77