Enhancement of antistatic properties of conductive carbon black/waterborne polyurethane UV-curable coatings by metal-organic framework materials

UV curable waterborne polyurethane (UV-WPUA) is a green, environmentally friendly, efficient and high performance polymer coating suitable for a wide range of substrates such as plastics, metals, paper, leather and so on. However, waterborne polyurethane itself is insulated, and with the accumulation of static charges, it can have adverse effects on equipment and human health, and even cause dangerous situations such as explosions and fires. Therefore, endowing waterborne polyurethane with anti-static properties has become a current hot topic. This study used conductive carbon black (CB) as a conductive filler for UV-WPUA to prepare UV curable coatings with anti-static properties. The surface resistivity of the coating can be further reduced by adding MOF-801, an organic framework material with varying levels of content. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR) were used to determine the structure of UV-WPUA. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the structure and microscopic morphology of MOF-801 and the dispersion of the MOF-801-CB/UV-WPUA coating. The results showed that the experiments were successful in synthesising UV-WPUA emulsion and MOF-801 materials. Under the constant temperature of 25℃ and humidity of 67% in the laboratory,the surface resistivity of the coating was 2.3×10⁶ Ω when the mass content of CB was 15 wt%. When 1 wt% MOF-801 is added to this coating, the surface resistivity of the coating decreases to 1.7×10⁵ Ω, the conversion of double bond is 70%, and the coating has good hardness and adhesion, meeting the requirements of anti-static coatings. It can be demonstrated that the addition of organic framework materials can further improve the antistatic performance of UV-cured coatings.