异氰酸酯改性环氧丙烯酸酯的合成及其光固化动力学的研究

采用两步法合成了可紫外光固化的异氰酸酯改性的环氧丙烯酸酯树脂,并利用元素分析、傅里叶变换红外光谱、核磁共振氢谱对此树脂的结构进行了表征。对树脂及其固化后涂膜的性能测试表明,合成的树脂具有较低的黏度,为4500mPa-s/60℃,固化膜柔韧性能优,低于3mm。采用红外光谱法对此改性树脂的光固化动力学行为进行了分析,结果表明:光引发剂Irgacure1000作为Darocur1173和Irgacure184以质量比1:1构成的复合型光引发剂,比单一的光引发剂具有更优异的引发效果;随着光引发剂Irgacure1000用量的增加,树脂体系光固化反应的聚合速率和树脂中双键的最终转化率都明显增加,但当其用量超过树脂质量的3%时,光固化反应速率和双键的最终转化率又趋于下降;活性单体对树脂光固化行为的影响为:单体的官能度越低、活性单体的用量越大,越有利于树脂的光固化,固化速率和双键的最终转化率都明显提高;此外,增大入射光的光照射强度也有利于树脂的光固化。

Synthesis and UV-Curing Kinetics of Epoxy Acrylate Modified by Isocyanate

UV curable epoxy acrylate resin modified by isocyanate (IEA) was prepared with epoxy resin, acrylic acid and isocyanate by two-step method. Elemental analysis, FT-IR and 1H-NMR were used to monitor the structure of the resin, it shows that the prepared resin has lower viscosity of 4500 mPa·s/60℃ and better flexibility below 3 mm. The UV curing kinetics of the resin was studied, and the results indicate that the Irgacure 1000, which is a kind of complex photoinitiators composed by photoinitiators Daeocur 1173 and Irgacurre 184 with mass ratio of 1:1, has the best photoinitiating effect because of its wider absorption band and possible synergistic effect of Daeocur 1173 and Irgacurre 184. The photopolymerization rate and the conversion ratio of the double bonds in the resin increase evidently with the increase of the used amount of photoinitiator Irgacure 1000, while when the used amount of Irgacure 1000 is more than 3%, the photopolymerization rate and the conversion ratio of the double bonds turn to be decrease with the further increase of the Irgacure 1000 amount used. It was found that the more the added amount of activating monomer and the lower the functionality of the activating monomer added, the lower the viscosity of the UV cured system. Since the viscosity of the cured system is the main factor affecting its UV curing behavior, adding more amount of activating monomer with lower functionality will favor the UV curing of the resin, which will increase the curing rate and the terminal conversion ratio of the -C=C- double bonds in the resin evidently. Moreover, increasing the light intensity of the UV radiation can benefit the photopolymerization of the resin too.