Study on the preparation of flame retardant plywood by intercalation of phosphorus and nitrogen flame retardants modified with Mg/Al-LDH

•Two new organic-inorganic flame retardants were synthesized and characterized. In addition, two phosphorus-nitrogen flame retardants were obtained by synthesis of Pyrovatex CP with urea and melamine, respectively, and were modified by intercalation with Mg/Al-LDH.•It was applied to formaldehyde-free API adhesives to prepare flame-retardant plywood materials.•The Mg/Al-LDH was prepared by the ion exchange method, and the unique laminated structure exerts a synergistic flame retardant effect. Moreover, this method has little impact on the strength of plywood.•The synthesized obtained flame retardant can exert the synergistic effect of phosphorus, nitrogen, and inorganic compounds, which can promote the formation of a cohesive phase and provide a continuous and compact char layer to stop the further burning of plywood.•It provides an environmental-friendly and simple method to prepare flame retardant wood materials for construction applications.