Preparation of Nano Al₂O₃ Coated Hollow Glass Microspheres Modified Polyurethane Composite Coating and Its Performance

Nano-Al₂O₃ was coated on the surface of hollow glass microspheres (HGM) by hybrid modification method, and composite powder with core-shell structure was prepared. Coating modified, silane modified and unmodified HGM polyurethane-based composite coatings were prepared by physical blending-spraying process. The effects of HGM modified by different methods and its content on the hydrophobicity and tensile properties of the composite coating were studied. The results showed that the agglomeration phenomenon of HGM after surface modification was alleviated. The interfacial adhesion with the substrate were improved. The coating modification significantly improved the surface roughness of HGM, the water contact angle increased from 60.37° to 118.35°. With the increase of filler content, the water contact angle of the composite coating increased, the tensile strength firstly increased and then decreased. When the coating modified HGM content was 10%, compared with the unmodified HGM, the water contact angle of composite coating increased from 74.5° to 90.3°, and the tensile strength increased from 2.07 MPa to 2.5 MPa.