Fluorescent brightener KSN and OB-1 have similar chemical structure, but the whitening effect on polyester fiber and plastic products is better than OB-1, and the compatibility with plastic is better than OB-1. It can produce very good whitening effect, which is far from OB-1. KSN not only has excellent high temperature resistance, but also has excellent solar and weather resistance. Fluorescent brightener KSN is also suitable for polyamide, polypropylene