The invention relates to a stable nanometer
silver colloidal sol and a preparation method thereof. The stable nanometer
silver colloidal sol adopts a silver containing compound, a protective agent and a
solvent, water is used as the
solvent, and the silver containing compound, the protective agent and the water are mixed so as to prepare the colloidal
sol; and the particle diameters of nanometer silver grains are 1nm-10nm, and the nanometer silver grains are uniformly distributed in the colloidal sol, and can be preserved for 6 months to 24 months without changing at
room temperature. The preparation method provided by the invention comprises the following steps of: adopting the silver containing compound and the protective agent as raw materials, adopting the water as the
solvent, mixing the silver containing compound, the protective agent and the water so as to form a
mixed solution which contains 200-10000ppm of silver, 0.02%-1% of protective agent, and the balance of water according to weight percent; and dissolving and mixing the components when the stable nanometer
silver colloidal sol is prepared, then uniformly stirring, conducting ultrasonic
processing, using a
light source containing
ultraviolet rays to light 30 minutes to 24 hours to obtain the nanometer silver colloidal sol containing the nanometer silver grains. The stable nanometer silver colloidal sol and the preparation method thereof provided by the invention have the advantages that the cost is low, the process is simple, and the stable nanometer silver colloidal sol is suitable for large-scale preparation.