Optically variable coating and preparation method thereof

The invention discloses an optically variable coating and a preparation method thereof. According to the method, raw materials are easy to obtain, the process is simple, cost is low, energy consumption is low, implementation is easy, and silicon dioxide particles with the particle size having the normal distribution characteristic are generated with ethyl orthosilicate as a silicon source, absolute ethyl alcohol as a solvent and ammonia water as a catalyst. A silicon dioxide colloidal solution with a certain mass fraction is prepared, and the silicon dioxide photonic crystal structure color is generated on a transparent film base material through self-assembly. The whole preparation method is mild in reaction condition and easy to implement, a precursor multi-step dropwise adding method is adopted, the synthesis rate of silicon dioxide is controlled through bidirectional dropwise adding in the reaction process, finally, the angle dependent type silicon dioxide photonic crystal is prepared, the structural colo