Synthesis of porous polyurea microspheres for matting coating

A type of porous polyurea microspheres for matting coating were prepared by precipitation polymerization in H 2 O/Acetonitrile (AN) solution, using isophorone diisocyanate (IPDI) as polymerized monomer, 2, 4-diaminobenzenesulfonic acid sodium salt as hydrophilic monomer and polyvinylpyrrolidone (PVP) as porogen. The effect of the type of porogen, reaction temperature, dry methods, post-perforation method and polyvinylpyrrolidone loading on the surface porosity was investigated. Meanwhile, the effect of the surface porosity and roughness of microspheres on the matting properties of the coating was also investigated. The results indicated that PVP porogen has played an important role in regulating the surface porosity of microspheres and shows superior perforation. When 15 wt% PVP (based on isophorone diisocyanate loading) was used as porogen, the reaction was carried at 50 °C in a shorter time, and the crude product was dried in a state of water dispersion at 100 °C, the resultant microspheres with maximal porous surface can be achieved. Post-perforation can further increase the surface roughness and porosity of polyurea microspheres without changing its particle size. When 5 wt% porous polyurea microspheres were added to the water-based polyurethane (WPU) coating, the gloss of the coating decreased from 6.27° to 1.14° (60° incident angle). Graphical Abstract