Flame-retardant urethane resin composition

A method for producing a flame-retarding composition, comprising a urethane resin prepared from a composition, the method comprising:

• preparing an additive by mixing red phosphorus and at least one selected from the group consisting of a phosphoric acid ester, a phosphate-containing flame retardant, a bromine-containing flame retardant, a boron-containing flame retardant, an antimony-containing flame retardant, and a metal hydroxide;
• preparing a mixture by mixing a polyol compound, a trimerization catalyst, a foaming agent, a foam stabilizer, and the additive;
• wherein the additive comprises at least one of:
• the phosphate-containing flame retardant in an amount within a range of 6.0 parts by weight to 52 parts by weight;
• the bromine-containing flame retardant in an amount within a range of 3.0 parts by weight to 52 parts by weight;
• the boron-containing flame retardant in an amount within a range of 6.0 parts by weight to 52 parts by weight;
• and
• the antimony-containing flame retardant in an amount within a range of 3.0 parts by weight to 52 parts by weight,
• based on 100 parts by weight of the urethane resin,
• wherein the phosphate-containing flame retardant is a phosphate composed of a salt of at least one kind of phosphoric acid selected from the group consisting of monophosphoric acid and pyrophosphoric acid, and at least one kind of metal or compound selected from the group consisting of metals of groups IA to IVB in the periodic table, ammonia, an aliphatic amine, and an aromatic amine, and
• wherein the bromine-containing flame retardant is at least one selected from the group consisting of hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenylether, octabromodiphenylether, hexabromodiphenylether, ethylene bi s (pentabromophenyl), bis(pentabromophenoxy)ethane, ethylene bis(tetrabromophthalimide), brominated polycarbonate, a brominated epoxy compound, poly(brominated benzyl acrylate), brominated polyphenylene ether, brominated polystyrene, and crosslinked or non-crosslinked brominated poly(methylstyrene);
• wherein the boron-containing flame retardant is at least one selected from the group consisting of borax, boron oxide, and boric acid, and
• wherein the antimony-containing flame retardant is at least one selected from the group consisting of sodium antimonate, potassium antimonate, sodium pyroantimonate, and potassium pyroantimonate;
• and
• adding a polyisocyanate compound into the mixture,
• wherein the trimerization catalyst is at least one selected from the group consisting of a carboxylic acid alkali metal salt, a tertiary ammonium salt, and a quaternary ammonium salt, and
• wherein an isocyanate index of the urethane resin is within a range of 200 to 1,000, and
• wherein an amount of the trimerization catalyst is within a range of 0.6 parts by weight to 10 parts by weight based on 100 parts by weight of the urethane resin, and an amount of the red phosphorus is within a range of 3 parts by weight to 18 parts by weight based on 100 parts by weight of the urethane resin.