Synthesis and application of aminosiloxane‐modified cationic waterborne polyurethane as fixing agent for nylon fabric

Abstract In order to make up for the lack of washing fastness and chlorinated water fastness of nylon dyed with acid dyes, an aminosiloxane modified cationic waterborne polyurethane (KWPU) with the ability to reversibly adsorb chloride ions was synthesized. N ‐methyldiethanolamine and ethylenediamine was used as chain extender. N ‐aminoethyl‐ γ ‐aminopropyltrimethoxysilane was used to block the remaining isocyanate groups and provide secondary amine groups for reversible adsorption of chloride ions. The structure of KWPU was characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), 1 H NMR, and differential scanning calorimetry (DSC). Particle size and zeta potential were tested to evaluate the emulsion stability. The research results showed that when the N ‐methyl diethanolamine content was 14%, the water absorption rate of KWPU film was 82.1%, and when the KH‐792 content was 6%, the water absorption rate of KWPU was 34.8%. The addition of siloxane can significantly improve the thermal resistance of the KWPU film. The color fastness of the dyed nylon fabric treated with KWPU emulsion was significantly improved, the rubbing fastness was improved by 0.5 or 1 grade, the washing fastness was improved by 1 grade, and the fastness to chlorinated water was improved by 1.5 or 2 grade.