METHOD OF PRODUCING FLAME RETARDANT FOAMABLE STYRENE BASED RESIN PARTICLE

PROBLEM TO BE SOLVED: To provide a method of producing a flame retardant foamable styrene based resin particle the flame retardant performance of which is not deteriorated and which is not decomposed during melt mixing in an extruder, and which uses a flame retarder having excellent environmental compatibility.SOLUTION: The method of producing the flame retardant foamable styrene based resin comprises: supplying ≥0.5 pts.wt and ≤15 pts.wt mixture of a bromine based flame retarder with a stabilizer and ≥3 pts.wt. and ≤10 pts.wt. foaming agent with respect to 100 pts.wt. styrene based resin to the extruder; then extruding the molten resin melt mixed in the extruder to a cutter chamber filled with a circulating water through a die attached to the tip of the extruder and having many small holes; and cutting the molten resin by a rotating cutter in contact with the die, immediately after the cutting. In the method, 1% weight loss temperature of the mixture of the bromine based heat flame retarder with the heat stabilizer in a thermogravimetric analysis is ≥2°C higher than that of the bromine based flame retarder alone and the foaming agent is a least one kind of ≥3C and ≤6C hydrocarbon.