Low-density high-strength flame-retardant adhesive

The invention discloses a low-density high-strength flame-retardant adhesive, which is prepared from the following raw materials in parts by weight: 20 to 25 parts of polyvinyl formal adhesive, 3 to 5 parts of simethicone, 10 to 15 parts of flame retardant, 80 to 90 parts of modified mixed filler, 5 to 7 parts of methyltris (methylethylketoximino) silane, 1 to 3 parts of coupling agent, 0.3 to 0.5 part of chain extender and 0.1 to 0.3 part of catalyst, in the preparation process of the low-density high-strength flame-retardant adhesive, the modified mixed filler prepared by mixing the modified nano calcium carbonate and the wet-process ultra-fine heavy calcium carbonate is added, and the wet-process ultra-fine heavy calcium carbonate agglomerated particles are small in specific surface area, small in number of active groups on the surfaces of the particles and small in generated bonding force, so that the elongation at break of the silicone adhesive is increased, and the flame-retardant property of the silico