a. Enhance the absorption of ultraviolet light by fluorescent whitening agent.
b. Make the fluorescence intensity of the association compound exceed the limit that can be achieved by using the fluorescent whitening agent alone.
c. Through the intermolecular association, the fluorescent whitening agent molecules are attached to the pvp chain of the macromolecules, which reduces the loss of the fluorescent whitening agent during the processing of photographic paper, so it has a whitening effect.