Preparation and characterization of waterborne polyurethane nail enamel modified by silane coupling agent

Intended for preparing silane-modified waterborne polyurethane dispersions and then applying them to the development of environmentally friendly nail enamels, the synthesis mechanism was investigated in this paper to determine the optimal technological parameters. Aimed at the synthesis of waterborne polyurethane dispersions, a one-step method was conducted on the prepolymers and the main raw materials, isophorone diisocyanate (IPDI), polycaprolactone diol (PCL), 1,4-butanediol (BDO), 2,2-dimethylol butyric acid (DMBA), (3-aminopropyl) triethoxysilane (APTES), triethylamine (TEA) and solvent water, were adopted. Subsequently, the water-based nail enamel together with its dry film was prepared by pigments and functional additives. Morphological characteristics and chemical composition of dry film of nail enamel were characterized by using atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The crystallinity of film was analyzed by an X-ray diffractometer (XRD). Benefiting from a thermogravimetric analyzer (TG) and differential thermal analyzer (DSC), the thermal properties of the prepared film were characterized. The hardness, adhesion, glossiness, water absorption, drying time and some other indicators of the water-based nail enamel were tested using a loading pencil hardness tester and other equipment. The experimental results showed the waterborne polyurethane modified by silane coupling agent exhibited favorable film-forming property, glossiness, flexibility, hardness, and adhesion and can be used for developing the environmentally friendly water-based nail enamel with a concentration of silane coupling agent of 1.5%, showing a broad market prospect in the cosmetics field.