Composite flame retardant and preparation method and application thereof

The invention relates to the technical field of wood processing, in particular to a composite flame retardant, a preparation method thereof and application for producing flame retarding plywood.The composite flame retardant is prepared from, by weight, 10-16 parts of ammonium sulfate, 2-8 parts of diammonium hydrogen phosphate, 1-5 parts of boric acid, 1-5 parts of zinc borate, 1-4 parts of magnesium oxide, 1-3 parts of aluminum sulfate and 2-8 parts of aluminum hydroxide.The composite flame retardant has the advantages that all the raw materials have the synergistic flame retardant effect, the flame retardant effect is good, toxicity is low, smoke suppression performance is good, and the composite flame retardant is environmentally friendly, and the price is low; the flame retarding plywood prepared through the composite flame retardant can remarkably improve the flame retardant performance of the flame retarding plywood, and the requirement for the national standard waterproof level-C or above can be met; the composite mechanical performance is higher than that of the national standard.