Studies on change of heating the synthetic coatting resins. II: Change on heating of dimethylol ether and dibutylol ether of dimethylolurea

Authors investigated the change on heating of dimethylolurea dimethyl ether (ME) and of dimethlolurea dibutyl ether (BtE) which were heated up to around 600°C from room temperature at average rate of 10°C per minute, and thermal change during the heating was pursued by differencial thermal analysis (DTA) and the loss on heating by means of thermogravimetric analysis (TGA). Samples, at every interval of 5 percent decrease in the weight, were quenched for elementary analysis of carbon, hydrogen and nitrogen, and for infra-red absorption spectral analysis (IR) and the composition was discussed. Further measurement was carried out for the alcohol or formaldehyde at every 5 percent decrease of the interval which were evolved during the heating, and were analysed by the use of gaschromatograph (GC) for the former and the colorimetry for the latter. With ME, the DTA showed the first, the second and the third endotherme. With TGA there could be seen the first (seen in the former half of the second endotherme indication by the DTA) and the second weight-decreasing bounds (seen in the latter half of the second endotherme of DTA) and the third slowly decreasing bounds (seen as the third endotherme of the DTA). The first endotherme at 105 deg. C of the above was that caused at the melting point. The second, from TGA, IR, elementary analysis and from the measurement by GC, was recognized as that there occurs two stage reaction to be explained as follows : During 130-180°C, methanol-escaping reaction proceeds as generally represented by the following equation, and at around 180°C the reaction velocity was lessened. 2-NHCH2OR→NHCH2-N-CH2OR+ROH (1) Further and violent reaction of the methanol escape occured at bounds 180-210°C with consequent disappearance of almost of the methoxy radical as follows : NHCH2OR→+O2-NHCH--OR-OOH→NHCOOH+ROH (2) The third endotherme is believed as the decomposition of urea structure. In case BtE the first, second and the third endotherme were observed by DTA, and the TGA measurement showed the first (seen in th former half of the second endotherme indicated by DTA) and the second weight-decreasing bounds (seen in the latter half of the second endotherme of DTA) and slowly decreasing third bounds (the third endotherme of DTA). The first endotherme is a sharply indicated peak at 97°C, being to melting point. The second begins from around 120, C and shows peak at 200°C ending at around 220°C which indicates a broaden endothermic bounds, of which