| Epoxy resin is a kind of thermoplastic resin with linear structure, and the curing agent should be added to it before practical application. After the polymerization reaction between curing agent and the epoxy group of the epoxy resin under certain conditions, the polymer which has the newly formed three-dimensional net structure showed a variety of excellent performances. There were many different kinds of curing agents. Aliphatic amine curing agent was the most widely used in daily life. It could be cured at low temperature and the curing time was short. However, weak points of the aliphatic amine curing agent were gradually found, such as toxicity, frangibility of the film, poor impact resistance and mechanical properties. Amine modified by Mannich reaction had become the new environmental trends of the development of new friendly epoxy curing agents. Mannich reaction was a class of the dehydration reaction among of the phenol, aldehyde and amine groups. The film of MXDA mannich bases had the advantages of shot curing time at low temperature and high hardness. It has been widely applied in coating, civil engineering and layers and materials.This dissertation aimed to prepare the new MXDA Mannich bases containing the flexible long alkyl chains by dehydration-condensation reaction from nonylphenol, formaldehyde and m-xylylenediamine in the condition of acid-catalyzed. Attentions had been paid to the effection of a series of experimental factors, such as the material ratio, reaction time, reaction temperature and dehydration pressure, on the performance of the product. We got the optimum synthetic conditions of mannich bases curing agent by designing orthogonal experiment, and the performance difference between our products and other similar samples were also discussed. The concrete research contents were as follows:(1) Sample1#was characterized by FTIR and1HNMR. The result shows that there weren’t exit stretching vibration of C=O(1705～1725cm-1) in FTIR and-CHO in1HNMR, which suggested that there is no carbonyl in product and formaldehyde reaction completely. However,-CH2-can be found in it. Therefore, we can conclude that the flexible long alkyl chains were successfully introduced to the main chain of curing agent by the means of dehydration-condensation. Three samples whose viscosity were10856mPa-s(B5),4339mPa-s(B2) and1734mPa-s(B10) were characterized by GPC, which suggested that the Mn were2386,1464,945.(2) Attention had been paid to the influence of the material ratio, reaction time, reaction temperature and dehydration pressure on the performance of curing agent by the means of single factor. The result showed that the incremental of the amount of methanol, the reaction time, the reaction temperature and the dehydration pressure can promote the reaction and lead to the reduce of amine value and the increment of viscosity. While the increment of the amount of MXDA will lead to the increment of amine value and the reduce of viscosity. The optimum synthetic process conditions of mannich bases curing agent was decided, which showed that the n(Nonylphenol): n(Formaldehyde): n(m-xylylenediamine)=1.0:1.2:1.3of material ratio,90℃of reaction temperature,2h of reaction time,0.0098MPa of dehydration pressure. The amine value was about330mgKOH/g and the viscosity was about4803mPa-s in the above condition. the Mn was1730.(3) Sample2#was used with E44. The result showed that the surface drying time of film reached to75min, the hard drying time reached to190min. The surface drying time reached to30min and the hard drying time reached to80min when2#samples as epoxy resin curing agent with DMP-30. And the thermal resistance of product was345.7℃by TGA. Compared with other curing agents,2#-EP had the advantages of acid, alkali and water resistance. The adhesion was O level, the pencil rigidity was5H, and the resistance impact was45kg·cm. Compared with other curing agents,2#-EP had the advantages of good impact resistance and chemical resistance. |
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