The application discloses a modified
mildew-proof agent, a
mildew-proof
sealant and a preparation method of the
mildew-proof
sealant. The modified mildew-proof agent is obtained by the reaction of an
alkali metal salt of 1,2-benzisothiazolin-3-one and chlorotrimethoxysilane. The mildew-proof
sealant comprises an A component and a B component. The A component is prepared from raw materials comprising
silane modified polyether, reinforcing filler,
fumed silica, thixotropic agent, the modified mildew-proof agent, light stabilizer and
plasticizer. The B component is prepared from raw materials comprising reinforcing filler,
plasticizer,
coupling agent and catalyst. The modified mildew-proof agent greatly improves the compatibility with the
silane modified polyether resin, and when added into the
silane modified polyether resin, the
mechanical strength and other comprehensive properties of the obtained mildew-proof sealant are not affected, the mildew-proof effect is greatly improved, the obtained mildew-proof sealant has excellent mechanical properties, good elasticity, good mildew-proof performance and good yellowing resistance.