Fire retardant coatings are also called flame retardant coatings. Plastic itself is a kind of polymer material, which belongs to flammable substances. Adding effective flame retardant into plastics and coatings can achieve the purpose of fire prevention. AlbertoFina et al. added some aluminum-containing isobutyl silsesquioxane (Al-POSS) to PP as a flame retardant, which has obvious flame retardant effect compared with PP without Al-POSS after combustion. Wang Huajin and others developed an ultra-thin fire retardant coating suitable for the surface of plastic products with modified highly chlorinated polyethylene resin as film former, pentaerythritol as charring agent and ammonium polyphosphate as charring catalyst, which has excellent fire resistance. Wang Min and others added amide and guanidine to the resin to develop a fire retardant coating. When heated, amide and guanidine components decompose to produce a large number of nonflammable gases, such as NH3 and CO2. These gases blow the molten substance into an expanded foam layer, which has a strong isolation function (heat insulation and gas insulation) and protects the substrate, making it difficult to reach the combustion conditions, thus effectively preventing fires. China patent 1060859A also introduces a foam mainly composed of formaldehyde, urea, sodium hydroxide, melamine, dicyandiamide, pentaerythritol, phosphoric acid, triethanolamine and hydrochloric acid.