PURPOSE: To produce a polyurethane having flame retardancy and good properties, by using a specified flame retardant as an active hydrogen-containing compound and reacting it with an organic isocyanate.
CONSTITUTION: In producing a polyurethane from an active hydrogen-containing compound, an organic polyisocyanate and other compounds, at least part of said active hydrogen-containing compound is a decomposition product (preferably one having a viscosity of 500W50,000cps/25°C and an OH value of 100W600mg KOH/ g) obtained by heatig polyethylene terephthalate in a polyhydric alcohol (e.g., diethylene glycol). This decomposition product functions as a flame retardant, so that a flame-retarding polyurethane can be obtained. A polyurethane in which a conventional nonreactive flame retardant is used softens and decreases its strength and can not retain its flame retardancy for a long time. This flame- retarding polyurethane is freed from these drawbacks.
YATSUGI SHIGERU
MATSUBARA KIYOSHI
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