Synthesis Of Liquid MOCA And Its Application In Polyurethane Elastomer

MOCA is an important chain-extender in the preparation of polyurethaneelastomer (PUE). However, MOCA must be heated up to110oC to make it to becompletely melted. MOCA could be oxided at heating for long time, and its colorcould be changed and affect on the properties of PUE. Therefore, to improve theapplication performance of MOCA, it is significant in practice to lower the meltingpoint of MOCA. In the paper, liquid MOCA was synthesized from o-chloroaniline,formaldehyde as main raw materials, and aniline,2,5-dichloroaniline,2,6-dichloroaniline as auxiliary raw materials. The performance at lower temperature,amine value and structure of the synthesized liquid MOCA was characterized,respectively. The polyester or polyester polyurethane prepolymer was extended by thesynthesized MOCA as chain-extender. The application performance of the synthesizedMOCA was evaluated through technology and property of PUE. Finally, the excellentkind of the synthesized MOCA was obtained.The o-chloroaniline was replaced with the mixture, which was formed from o-chloroaniline, aniline,2,5-dichloroaniline and2,6-dichloroaniline in differentproportion. The18kinds of liquid MOCA were synthesized through salt-forming,condensation, neutralization, rinsing and vacuum drying and the like. The results wereas followes: all the synthesized samples were liquid at25℃; MOCA was mainingredient in the synthesized samples and other diamine compounds were minorconstituent; the FTIR spectrogram of the synthesized sample was almost the same withthat of MOCA.On the basis of discussing the synthetic liquid MOCA extending polyether-polyurethane prepolymer, the three better kinds of liquid MOCA were chosen. Thepolyether PUE (or polyester PUE) was prepared with the polyether-(or polyester-)polyurethane preploymer extended by the above three kinds of the synthetic liquidMOCA, and the physical, thermal and crystalline properties of the PUEs were characterized. The results were as follows:1Under the fixed molar ratio of amine mixture and formaldehyde being2:1, theliquid MOCA of excellent performance was synthesized when the mass ratio of o-chloroaniline, aniline and2,5-dichloroaniline (or2,6-dichloroaniline) was90:5:5, orwhen the mass ratio of o-chloroaniline, aniline,2,5-dichloroaniline and2,6-dichloroaniline was85:5:5:5.2with increasing of adding amount of three synthetic liquid MOCA as chain-extenders, the tensile strength and hardness of polyether PUE (or polyester PUE)enhanced, but its elongation lowered. Specially, the liquid MOCA as chain-extenderwas synthesized when the mass ratio of o-chloroaniline, aniline,2,5-dichloroanilineand2,6-dichloroaniline was85:5:5:5, the tensile strength of polyether PUE was up to18.87MPa, the elongation at break being up to713%, and the tensile strength ofpolyester PUE was up to21.76MPa, the elongation at break being up to400%.3Polyether PUE and polyester PUE were crystalline polymer. Tg and thermaldecomposition temperature of polyether PUE was lower than those of polyester PUE.