A New Technology For Removing Trace Water From Polyether Component And Its Application In RIM-PUE

RIM polyurethane elastomers (RIM-PUE) with excellent properties have been widely used in automobile field. The influences of water on material properties are significant in the preparation of RIM-PUE, so reducing water content of polyether component is critical in order to achieve RIM-PUE with higher properties. Sb₂(OCH₂CH₂O)₃ is a organo-metallic compound, which can be decomposed to Sb₂O₃ and ethylene (EG) when encountering water. Sb₂O₃ is able to reinforce RIM-PUE materials and has the flame retardant performance, while EG can be used as a chain extender. So the water-removal efficiency of Sb₂(OCH₂CH₂O)₃ and the application of Sb₂(OCH₂CH₂O)₃ in RIM-PUE were studied in this paper.In the experiment,Sb₂(OCH₂CH₂O)₃ was refined in the combined polyether by the sand milling disperser. Then the settling characteristics of Sb₂ (OCH₂CH₂O)₃ with different particle sizes in the combined polyether were discussed, and the influence of temperature on the viscosity of the combined polyether was investigated. Meanwhile the water-removal efficiency of Sb₂(OCH₂CH₂O)₃ in different systems were studied systematically. Based upon above the studies, RIM-PUE materials were made from high active polyether, liquefied MDI, EG and amino-dibutyltin complex catalysts. The catalytic activity of Sb₂(OCH₂CH₂O)₃ with different particle sizes was studied, the influence of Sb₂(OCH₂CH₂O)₃ content and technological conditions on the process, properties and microstructure of RIM-PUE materials were also discussed.The results were as follows. (1) With the prolongation of dispersing time of Sb₂(OCH₂CH₂O)₃ particles in the combined polyether, the sizes of Sb₂(OCH₂CH₂O)₃ particles were reduced, and the settling performance of Sb₂(OCH₂CH₂O)₃ particles in the combined polyether became not more obvious. When the dispersing time was up to 20min, the Sb₂(OCH₂CH₂O)₃ particles in the combined polyether didn't settle for 48h and the particle diameter of Sb₂(OCH₂CH₂O)₃ was about 200nm. Moreover, with the prolongation of dispersing time, the viscosity of the combined polyether containing Sb₂(OCH₂CH₂O)₃ was obviously increased. (2) The effect of temperature on the viscosity of the combined polyether containing Sb₂(OCH₂CH₂O)₃ was significant. The viscosity of the combined polyether was dramatically decreased with the increasing of temperature, the viscosity was about 600mPa·s at 60℃and was similar to that of liquefied MDI at room temperature. (3) Sb₂(OCH₂CH₂O)₃ had excellent water-removal efficiency in the combined polyether and the pure polyether, but the dehydration rate in the combined polyether was faster. The reaction parameters bewteen Sb₂(OCH₂CH₂O)₃ and water were following: reaction order n=2, active energy Ea=22.12 kJ/mol and Arrhenius equation lgKc=6.0415-1155.93/T. (4) the refined particles of Sb₂(OCH₂CH₂O)₃ had higher catalytic activity in the preparation of RIM-PUE materials, and when the Sb₂(OCH₂CH₂O)₃ content in the combined polyether was the same, the smaller particle sizes were, the shorter cream time and gelation time of the RIM-PUE polymerization were. Meanwhile, with the increasing of Sb₂(OCH₂CH₂O)₃ content in the combined polyether, both cream time and gelation time of the RIM-PUE polymerization became shorter, density and hardness of RIM-PUE materials were slightly enhanced, and tensile strength and elongation at break were obviously increased. (5) With the prolongation of mixing time of Sb₂(OCH₂CH₂O)₃ with the combined polyether and the increasing of temperature of the combined polyether, cream time and gelation time of RIM-PUE polymerization were shorter, density and hardness were slowly increased, and tensile strength and elongation at break were improved significantly. (6) SEM photos showed that the refined particles of Sb₂(OCH₂CH₂O)₃ were well-dispersed in the RIM-PUE materials, and agglomeration of the refined particles of Sb₂(OCH₂CH₂O)₃ was not obvious. XRD showed that the crystalline characteristic of Sb₂(OCH₂CH₂O)₃ in RIM-PUE matrix disappeared. TG demonstrated that the heat-resisting performance of RIM-PUE containing Sb₂(OCH₂CH₂O)₃ could be improved.