The invention discloses a preparation method for a composite modified facing protective layer. The preparation method comprises the following step (1) of
coating base materials on a carrier by spraying, and baking the carrier; and the step (2) of
coating surface materials on the bottom layer by spraying, and baking the bottom layer. The base materials and the surface materials are both prepared from inorganic light diffusants and water glass, the
mass proportions of the inorganic light diffusants and the water glass in the base materials and the surface materials are different, and the particle sizes of the inorganic light diffusants in the base materials and the surface materials are different. Due to the difference of the particle sizes and
mass concentrations of light diffusant materials of different
layers in a multi-layer structure, longitudinal distribution of media is not uniform, a scattering phenomenon is very easy to occur, and the
haze is improved while the light
transmittance is ensured. A method of
coating one layer and baking one layer is adopted, and since each layer is thin, on one hand,
water vapor is easy to release, and on the other hand,
water vapor needing to be released is less; the problem of surface bulging in the baking process is solved, and the problem of
water resistance of water glass is solved through a baking process.