Study On Solvothermal Catalytic Degradation Of Waste Rigid Polyurethane Foam And Preparation Of Regenerative PU Foam

In this paper,the process of solvothermal catalytic degradation of waste polyurethane rigid foams to prepare polyether polyols was first studied.And the effects of process parameters such as the type of liquefier,reaction temperature,reaction time,mass ratio of raw materials to liquefier and catalyst dosage on the hydroxyl value of the liquefied products were investigated.Optimized liquefaction parameters were determined:?1?Optimal conditions for catalytic solvent thermal degradation with EG as the liquefier:the reaction time is 4 h and temperature is 200?,the dosage of catalyst A₁ is3.0%,the ratio of solid-liquid is 1:3,hydroxyl value is 327.6 mgKOH/g,viscosity is 586.0cps and moisture is 0.05%;?2?Optimal conditions for catalytic solvent thermal degradation with EG and PEG200as the liquefier:the reaction time is 4 h and temperature is 180?,the dosage of catalyst A₁is 3.0%,the ratio of solid-liquid is 1:2?3:7?,hydroxyl value is 366.9 mgKOH/g,viscosity is819.0 cps and moisture is 0.05%;?3?Optimal conditions for catalytic solvent thermal degradation with PEG-200 and glycerin as the liquefier:the reaction time is 8 h and temperature is 180?,the dosage of catalyst A₁ is 3.0%,the ratio of solid-liquid is 1:3?7:3?,hydroxyl value is 433.4 mgKOH/g,viscosity is 1025.0 cps and moisture is 0.05%.And then,the structure of the liquefied product was analyzed and confirmed.At all cases,complete degradation of the foam achieved,and the degradation in PEG-200 and glycerin system shown best effect,identification of the liquefied product is conducted.The liquefied product polyol partially replaces the 4110 polyol and reacts with diphenylmethane diisocyanate?MDI?to prepare regenerated rigid polyurethane foams with water as the foaming agent.The effects of the proportion of polyol replacement on the microstructure,apparent density,thermal stability and mechanical properties of recycled rigid polyurethane foams were investigated.When the replacement amount of the liquefied polyol is 20%,the complex property of the regenerated foam fully meets the requirements of the national standard for rigid thermal insulation polyurethane materials.This method provides a feasible way for the efficient utilization of waste rigid polyurethane foams.