Water-based anti-discoloration sealing agent for silver plating layer, anti-discoloration film and preparation method of anti-discoloration film

The invention belongs to an anti-discoloration sealing agent, and provides a water-based anti-discoloration sealing agent for a silver coating, an anti-discoloration film and a preparation method of the anti-discoloration film in order to solve the technical problems that an existing silver anti-discoloration agent can only prolong the discoloration time and reduce the discoloration degree and is poor in high-temperature stability, and a treated silver-plated part is poor in acid resistance and salt mist resistance. The anti-discoloration sealing agent comprises yttrium-zirconium composite sol, a silane coupling agent, alkyl mercaptan, an emulsifier, a wetting agent, a penetrant and water, has double functions of preventing silver discoloration and sealing holes of a silver coating through verification, can remarkably improve the anti-discoloration capacity and acid and salt mist resistance of the silver coating, has very high high-temperature stability and can endure baking at the high temperature of 900 DEG