Preparation and Properties of Halogen-Free Flame Retardant Polyurethane for Superfine Fiber Leather

Polyurethane (PU) superfine fiber leathers have been widely used in people's life. However, the flammability brings potential risks to their application. Therefore, more and more attention has been paid to the flame retardant modification of PU leathers. In the 1980s, researchers found that some brominated flame retardants produced dioxins during combustion. In 2007, the EU began implementing the REACH regulation, which restricted the use of certain halogenated flame retardants, so a majority of studies focused on halogen-free flame retardant modification. In addition, the halogen-free flame retardant PU should own a better alkali resistance, because alkali treatment is needed in the forming process of the superfine fiber leather. In this paper, two different halogen-free flame retardants were blended with solvent-based PU. The flame retardant properties and alkali resistance of the flame retardant PU were studied by limiting oxygen index (LOI) test, vertical burning (UL-94) test, and thermogravimetry-infrared spectroscopy (TG-FTIR). It was found that BY-90 system flame retardant could be uniformly dispersed in the PU matrix. And when its additive volume was 27%, the LOI value of the flame retardant PU was 27.1%, the vertical burning test could reach V-0 level. Moreover, it also had good alkali resistance. The LOI value remained at 26.1% after the alkali treatment at 90 °C for 40 min in the 30g/L NaOH solution.