Research On Synthesizing Polyether Polyol Through Alkylene Oxide Ring Opening Polymerization Catalyzed By Modified Zn-Co DMC

Polyether glycol is the main material of producing PU foamy plastic, of which the demand maintains rapid growth. The synthesis of polyether glycol nowadays mainly depends on the technology of the ring opening polymerization of alkylene oxide catalyzed by traditional base (primarily KOH). However, the great quantity of K+ introduced by the catalyst itself requires the product to undergo sophisticated purification process, which raise the production cost largely. The inevitable isomerization of polymeric monomer in the reaction reduce the quality of the product.DMC is a new kind of catalyst for the ring opening polymerization of alkylene oxide, which is effective and environmental, making it a possible substitute for KOH. However, its deficiency also restrains its industrial application, for example it requires long induction period, needs low-polymer PPG as initiator, and gets no low PDI product when using EO to cap PPG. The article aims to overcoming the difficulties of industrial application, synthesizing high quality PPG which is low unsaturated, has controllable molecular weight and can be capped in the lab. It studies the following aspect:Modifying DMC. Using the modified DMC to catalyze the ring opening polymerization of PO and EO, triggering the reaction successfully with small molecular polyhydric alcohol which was thought to cause the inactivation of DMC. The induction period of PO is less than 30 minutes, and that of EO is less than 50 minutes, both lower than the reported values. After comparing the capacity of different initiators, the conclusion is drawn that fewer active sets and weeker coordination capability are more beneficial to initiate the reaction and produce PPG product with a wide spectrum of molecule weight for the initiators with similar molecule weight. Confirming the range of the molecule weight produced by each initiator through changing the Ini./PO(EO) in the lab and getting the conclusion that higher initiator concentration is not good for initiating process but good for the reaction rate and the stability of the whole reaction system.Multiplicative reaction has been performed for this reaction. Mass transfer and stability of catalyst are affirmed as the key restricting factors. Charging mixed liquid of initiator and PO in batches can lead lower pressure, stable reaction rate and scarcely affect PDI of production. For initiating reaction easily and synthesizing PPG in wide range, PEG was regarded as an excellent initiator.A breakthrough was achieved for EO capping PEG by using modified DMC catalyst. DMC catalyzed EO ring- opening polymerization was deemed to get production with high PDI, but modified DMC achieved low-PDI production by using PEG-400 as initiator. This result may help modified DMC to apply to industrial manufacture.