Synthesis And Properties Of Highly Dissolvable Toluene Diisocyanate Trimer And Its Application

On the base of mixed catalysts, a highly dissolvable toluene diisocyanate (TDI) trimer modified by butan-1-ol or 2-(2-butoxy-ethyoxy)-ethanol was synthesized. In the modified TDI-trimer, the solid content is about 50%, free TDI is less than 1.5%, and the tolerance of modified TDI-trimer to dimethylbenzene is over 2.0. This modified TDI-trimer can be used to prepare paints with different acrylic polyol resin. The paints prepared with modified TDI-trimer have smaller and more uniform particles than those prepared with unmodified TDI-trimer and are good enough to be applied in the PU furniture coating. Their performances can satisfy the criterions of GB18581-2001.In the light of experimental experience of NEWTECH Chem.Co.LTD, normal TDI-trimer was firstly synthesized. By comparing performances of different catalysts, it is found that the mixture of DMP-30 with tributyl - phosphane is the best catalyst for the synthesis of TDI-trimer.Highly dissolvable TDI-trimer was synthesized by modification of butan-1-ol or 2-(2-butoxy-ethyoxy)-ethanol. The reaction conditions were studied. The results show that good TDI trimer can be synthesised when the reaction temperature is 60 ℃, the dosage of catalyst is 0.1%, butan-1-ol or 2-(2-butoxy-ethyoxy)-ethanol is used and the mol ratio of -NCO/-OH is between 10:l~14:l. Moreover, it is found that free TDI content can be controlled under 1.0% when TDI raw material is used in batches.The experiment results of gel permeation chromatograph(GPC ) spectrum show that molecular weight of modified TDI-trimer is reduced, mainly distributing 600~2000g/mol. From the FTIR and GPC analysis of modified TDI-trimer, it can be concluded that there are main pentamer structures in the modified TDI-trimer. Thisalso explained why the modified TDI-trimer has better dissolvable ability with acrylic polyol resin. The thermal stability of TDI-trimer modified by butan-1-ol was studied by means of thermogravimetry analysis(TGA).The results show that the thermal stability can be improved by increasing the ratio of -NCO/-OH; there is less relations between the thermal stability and the catalyst kinds. However, the thermal stability can be improved if more catalysts are used.