▎ 摘　　要

NOVELTY - Foam board comprises 91-93 pts. wt. polyurethane resin, 14-16 pts. wt. polycarbonate, 11-13 pts. wt. polysulfone resin, 10-12 pts. wt. asbestos, 7-9 pts. wt. chitosan quaternary ammonium salt, 0.3-0.5 pts. wt. white carbon black, 0.14-0.16 pts. wt. graphene and 3-5 pts. wt. acetic acid solution. USE - The foam board is useful for food packaging (claimed). ADVANTAGE - The foam board: is safe and healthy, and environmentally friendly; has flexible insulation; inhibits growth of bacteria and to ensure that food is not destroyed by external forces and extends shelf life of food; has compression and tensile strength, flame retardant properties and lower foam thermal conductivity; and is low cost. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing foam board, comprising (1) heated polyurethane resin to 210-220 degrees C, and melting for 10-15 minutes to obtain molten polyurethane, (2) adding polycarbonate and polysulfone resin into the molten polyurethane, and melting at 190-200 degrees C for 30-35 minutes to obtain mixture A, (3) adding white carbon black and graphene into the mixture A, stirring at 200-210 degrees C for 10-15 minutes to obtain mixture B, (4) adding asbestos and chitosan quaternary ammonium salt into mixture B, stirring at 160-170 degrees C under vacuum condition, cooling to -6 degrees C to -4 degrees C, heating for 5-7 hours, crushing to 40-50 nm, adding acetic acid solution, then heated to 220-230 degrees C at a heating rate of 1.1-1.3 degrees C/minute, then melting completely to obtain mixture C, and (5) foaming and molding the mixture C based on existing process to obtain final product.