Industrial Implementation Of A Novel Process For Production Of High Viscosity Polymeric MDI

Polyisocyanurate foam (PIR) is a kind of the rigid polyurethane foam which has become one of promising building insulation products because of its light weight, good thermal insulation effect and easy installation. The high viscosity polymeric MDI, with a global market demand of more than 400KT per year, is the main raw material to produce PIR. However, it can’t produce high quality and enough high viscosity polymeric MDI to satisfy the demand through the present production process, including knockout tower process, short-path distillation process and thin-film evaporation process.Considering the merits and demerits of the previous process, the paper presents a new process of producing high viscosity polymeric MDI which combines knockout tower process and short-path distillation process together. It constitutes a process simulating model by ASPEN PLUS software and computes the composition of the important stream. According to the result of simulation, the design plan of producing high viscosity polymeric MDI is completed and has been applied into industrial production successfully. Meanwhile, it develops the analysis method to evaluate the relative content of dimer, dimensional stability and compressive properties of high viscosity polymeric MDI and perfect the whole evaluation system.Comparing with the traditional ones, "short-path distillation & knockout tower" process can solve these problems well, such as filler coke, low purity M, poor quality MDI, and produces quality high viscosity polymeric MDI stably. Its quality and capacity has achieved the design goal, met the demand of the downstream market and obtained great economic and social benefit.