Combustibility of Flame-retardant Rigid Polyurethane Foam — Experiments with Small Scale Samples —

Abstract

An experimental study on combustibility such as ignition and spread of spray-applied rigid polyurethane foam for thermal insulation (flame-retardant rigid PUF) was conducted. Polyurethane foams with the oxygen index of 23 and >26, which conform to JIS A 9526 Class A • 1H, were used. The main experimental items were as follows: TG-DTA thermal analysis, ignition with different igniters, ignition due to spatters (hot particles) generated by gas cutting, flammability on the thermal surface, flame propagation through pyrolysis gas/vapor, sample combination and flame spread (a small model experiment). As a result of the experiment on flame-retardant rigid PUF, the following is found. a) It is locally ignited and burned by gas-cutting spatters. However, it does not spread along the sample plate. b) Pyrolysis gas/vapor ignites when the hot surface temperature is 430°C or higher. c) Even flame-retardant rigid PUF can spread by combining sample plates.