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Polyurethane foaming machineUnder the catalysis of alkali metal hydroxide, water vapor with pressure of 50-150kpa is injected into waste soft foam at 250-340℃. Waste soft foam can be decomposed into amine, polyol and CO2. The degradation reaction formula is as follows:

Rl~～NHCOOR2+H2O

R1-NH2+R2OH+CO2

The resulting amine and CO2 are carried out by steam, and the amine compounds are recovered by condensation, while the alcohol compounds are collected from the lower part of the critter. Hydrolysis temperature is the guarantee of recovery yield and quality. It is reported that the optimal temperature is 288℃.

Due to access to this method is high pressure steam, so sometimes also called steam cracking method, the advantage of this approach is directly recovered species class, recycled polyols can be 5% of the preparation of soft foam, compared with conventional density, tensile strength and elongation increased, and just tear strength decreased. The disadvantage is that the hydrolysis temperature is relatively high, the obtained amine cannot be directly used in the production of isocyanate, and the polyol is difficult to alcoholize to the required standard, and the cost is high, so the method has not been industrialized.