Study Of Homogenization Of Conjugated-polyether And Its Effect On The Properties Of Polyurethane RIM Elastomers

Polyurethane RIM Elastomers (RIM-PUE) have been widely used in many fields beacause of their excellent mechanical properties and processing characteristics. The raw materials of polyurethane usually constituted by two components: polyether component (conjugated-polyether) and isocyanate component. The former included polyether polyol, chain extender, catalysts, additives, et al. Beacause compatibilities among constituents in the conjugated-polyether were different, especially compatibility between polyether ployol and ethylene glycol as a chain extender, the demixing phenomena of the conjugated-polyether in store and usage occured. The phenomena resulted in the poor properities of RIM-PUE articles and influenced the qualified rate of the articles and the production efficiency. In the paper, the demixing phenomena of the conjugated-polyether was solved with even disperants synthesized by self, and the homogenization and its effect on the processing technology and properties of RIM-PUE were carefully studied.Aliphatic diamine sulphonate (AAS salt) as an even disperant was synthesized of ethylene diamine and sodium 2-chloroethane sulfonate and N,N-bis(2-hydroxyethyl)-2-aminoethane sulphonate (BES sodium) as the other even disperant was synthesized of diethanolamine and sodium 2-chloroethane sulfonate. The above products were characterized by 1H NMR,13C NMR, FTIR, XRD, et al. The change of pH values in the reaction system was observed with reaction time. The best synthetical conditions of the even disperants were obtained. AAS salt was sythesized at 65~70℃for more than 50min. BES sodium was sythesized at 60~80℃for more than 60min when the molar ratio of diethanolamine and sodium 2-chloroethane sulfonate was1:1.1.The two even disperants were added to the conjugated-polyether constituted of high active polyether polyol and ethylene glycol, respectively. The homogenization of the even disperants on the conjugated-polyether was explored. On the basis, liquied MDI as isocyanare component, the effect of the even disperants on the processing technology and properties of RIM-PUE was systematically studied. The results were as follows. (1) When the content of AAS salt in the conjugated-polyether was 0.2% by weight, the homogenized effect of the conjugate-polyether was excellent, and the conjugated-polyether was not demixed for 42 days at room temperature. When the content of BES sodium was 0.05 wt%, the homogenized effect of the conjugate- polyether was better, and the conjugated-polyether was not demixed for 73 days at room temperature. In short, the homogenized effect of BES sodium was better than that of AAS salt. (2) Both AAS salt and BES sodium showed catalytic activity for reaction in the preparation of RIM-PUE to some extent. With the increasing of even disperant content, cream time and gelation time of the polymerization became shorter, tensile strength and hardness of RIM-PUE materials were enhanced, elongation at break was decreased. (3) The chain segment contained -SO3Na groups could be embeded in PU macromolecule in the presance of AAS salt and BES sodium, thus enhanced the cohesion strength between RIM-PUE material and surface coating. (4) XRD showed that the free AAS salt and BES sodium did not exist in RIM-PUE materials. When AAS salt and BES sodium were used, the heat resistance of RIM-PUE materials was improved.