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Recovery of polyurethane foaming agent by alkaline hydrolysis

Polyurethane foaming machineThe alkaline hydrolysis of recovery method based on alkali metal hydroxide, such as NaOH LiOH, KOH, Ca (OH) 2 as decomposition agent, one or more of the mixture with quaternary ammonium salt or sulfate activator, join containing pieces of soft foam resolver, heated to 160 ℃ under stirring, began decomposition reaction, continuous stirring insulation around 4 hours, can obtain alkaline hydrolysis product polyols, binary aromatic amine and sodium carbonate, etc. The decomposition equation is as follows:

Polyurethane foaming machine

R1~~NHCOOR2■

R1~~NCO+R2OH

R1~~NHCONH~~R2■

R1~~NCO+R2OH

R1~~NCO+2NaOH■

R1-NH2+Na2CO3

The whole process includes decomposition of foam, separation and recovery of toluene diamine, and purification and recovery of polyether polyols.Polyurethane foaming machineThe recovered toluene diamine can be used as raw material for photogasification reaction to produce isocyanate. The recovered polyols can also be directly used to prepare polyurethane foams and their properties are similar to those of conventional foams. Generally, the cleaned 1000kg soft foam can recover about 550kg of polyol and about 230kg of toluene diamine, with a high recovery rate. From the perspective of environmental protection and economy, alkaline hydrolysis is a better recovery method. But the disadvantage is that the reaction is carried out under the condition of high temperature and strong alkali.


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