Synthesis and application of flame retardant self-matting aqueous polyurethane dispersion

To address the issues of insufficient film smoothness, and flammability of aqueous polyurethane dispersions (PUD) prepared by adding matting agents, two hydrophilic chain extenders, dimethylolpropionic acid (DMPA) and sodium 2-[(2-aminoethyl)amino] ethanesulphonate (A95), were used to regulate the particle size of the emulsion while using FRC-6 flame retardant as a small molecule chain extender to prepare a self-matting and flame retardant PUD. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and atomic force microscopy were used to structurally characterize the latex films. The results showed that as the R-value (NCO/OH molar ratio) and soft segment content decreased, the prepolymer viscosity increased, making it difficult to emulsify and reducing the glossiness of the film. Moreover, an initial increase in DMPA content led to a decrease in film glossiness, followed by an increase. Increasing the molar ratio of A95 sulfonic acid salt-based chain extender to EDA affected the glossiness of the film, with a 2:8 molar ratio of A95: ethylenediamine (EDA) resulting in a glossiness of the film of 6.5%. The addition of reactive flame retardant diethyl bis (2-hydroxyethyl) aminomethyl phosphonate (FRC-6) increased the branching content in the prepolymer, improved the flame retardancy of the film, and reduced its glossiness. As a result, the self-prepared PUD had a flat film with a glossiness as low as 6.0% and a flame retardancy rating of level 4.