Borates are used in polymers to increase the flame retardancy of the products.  All resin systems used in polymers can benefit from the use of borates as a fire retardant.  Borates are used to inhibit flame combustion to produce char formation and suppress afterglow.  Borates have intrinsic molecular water which is released in a flame situation and thereby inhibits the flames.  The borates also form an incombustible char that insulates the fire situation from the fuel of the substrate and slows the release of combustible gases that also fuel combustion.   Since borates release water when heated, they also act as an afterglow suppressant which extinguishes any threat of an existing fire source.