Method for preparing composite film with high covering power

The invention discloses a method for preparing a composite film with high covering power. The method comprises the following steps: at first, ultrasonically dispersing commercially available TiO2 powder into a triethanolamine solution of casein to obtain casein/nano TiO2 mixed liquor, then adding a caprolactam aqueous solution to perform hydrophobic modification on the casein to obtain caprolactam modified casein/nano TiO2 composite emulsion, adding acrylate monomers and an initiator to polymerize to obtain casein based TiO2 nano composite emulsion, and finally performing film casting on the casein based TiO2 nano composite emulsion to obtain a casein based titanium dioxide composite film with high covering power. The preparation method disclosed by the invention is simple, the composite film with high covering power and good flexibility is obtained, meanwhile, the mechanical properties of the film are improved to a certain extent, the composite film can be used for decorating leather to improve the covering rate of the defects of the leather and beautify the appearance of the leather, and the composite film can also be used for modifying textile surfaces, so that the application prospect is very good.