Application Of Antimony Compounds In RIM Polyurethane Elastomers

As a branch of polyurethane materials, RIM polyurethane elastomers (RIM-PUE) have excellent mechanical performance, wear-resistance and chemical stability, so they can be widely applied as structural parts in various fields. But some performances in some practically applied fields are already overmuch, and other performances need to be enhanced to a certain extent, eg, tensile strength, elongation at break et al.. The factors on the performance of RIM-PUE were molding process, raw material specifications, etc. The effect of water content in polyether component on RIM-PUE is very significant. Sb₂(OCH₂CH₂O)₃ as a antimony compound can react with water to form ethylene glycol (EG) and Sb2O3. So it is an available way to reduce water content in polyether component, and Sb2O3 is a reinforcer in the RIM-PUE. Therefore, the application of antimony compounds in RIM-PUE was studied in this research.In the experiment, RIM-PUE was prepared by high activity polyether, liquefied MDI, EG, dibutyltin dilaurate and triethylenediamine as main raw materials. The effect of water, Sb₂(OCH₂CH₂O)₃ and Sb2O3 contents on the process, properties and microstructure of RIM-PUE were first discussed, respectively. At the same time, the solubility of antimony compounds in EG was tested. On the basis of the above research, the characteristics of Sb₂(OCH₂CH₂O)₃-water reaction was studied in detail, and the application of the combined polyether containing Sb₂(OCH₂CH₂O)₃ in the preparation of RIM-PUE was investigated. The results showed as follows. (1) With the increasing of water content, polymerization time was elongated, hardness of RIM-PUE materials was first increased slightly then decreased slowly, and density, flexural modulus, tensile strength and elongation at break of materials were all first decreased slowly then decreased significantly. The blowing trend of materials was more obvious. In order to get materials with higher properties, the content of water in combined polyether must be controlled in less than 0.1%. (2) With the increasing of Sb₂(OCH₂CH₂O)₃ content in the RIM-PUE/Sb₂(OCH₂CH₂O)₃ composites, density was slowly increased, hardness and tensile strength were increased more quickly, and elongation at break was first increased remarkably to 210% and then decreased. The crystalline performance of Sb₂(OCH₂CH₂O)₃ in RIM-PUE matrix didn't exist. With the increasing of Sb2O3 content in the RIM-PUE/Sb₂(OCH₂CH₂O)₃ composites, density, hardness and tensile strength were all enhanced slowly, but elongation at break decreased remarkably. The crystalline performance of Sb2O3 in RIM-PUE matrix still existed. When the additive level of Sb₂(OCH₂CH₂O)₃ in polyurethane system was the same as Sb2O3, Sb₂(OCH₂CH₂O)₃ had higher activity and obviously influenced the properties of RIM-PUE/Sb₂(OCH₂CH₂O)₃ composites. (3) Sb₂(OCH₂CH₂O)₃ reacted quickly with water in combined polyether system, didn't react in EG system and reacted slowly in polyether system. The parameters of Sb₂(OCH₂CH₂O)₃-water reaction were as follows: reaction order n=3, activation energy Ea=18.30kJ/mol, pre-exponential factor Kc0=5.81912×106, Arrhenius equation lgKc=6.7149-956.01286/T. The molar concentration of water in combined polyether system was first dramatically decreased in 1h, then slowly lowered. The solubility of Sb₂(OCH₂CH₂O)₃ in EG was higher than that of Sb2O3 in EG. (4) With the increasing of molar ratio of Sb₂(OCH₂CH₂O)₃ to water at the same preserving time or with the prolongation of preserving time of combined polyether containing Sb₂(OCH₂CH₂O)₃ at the same of molar ratio of Sb₂(OCH₂CH₂O)₃ to water, density and hardness of the two composites were partly increased, and tensile strength and elongation at break were significantly enhanced. The most particles of antimony compounds could be evenly dispersed in RIM-PUE matrix and there were a few agglomerates. (5) DSC data showed the addition of Sb₂(OCH₂CH₂O)₃ to PUE didn't changed the phase microstructure of RIM-PUE, but Tg of soft segment and hard segment of PUE was enhanced. TGA-DTA analysis showed that heat-resisting performance of PUE was improved to some extent.