三聚氰胺-甲醛树脂微胶囊成壁机理的探讨

A preliminary study on the shell-forming mechanism for melamine-formaldehyde microcapsules

选用表面光滑且呈规则球形的玻璃微珠作为芯材,排除芯材不稳定性对原位聚合成壁过程的影响,利用扫描电镜观察反应时间、反应温度和催化剂用量对壁材微观形貌的影响,探讨三聚氰胺-甲醛树脂微胶囊的成壁机理。结果表明,随着反应时间的延长,粒径小于200 nm的树脂颗粒逐渐覆盖在芯材表面形成壁材。反应温度的升高和催化剂用量的增加对壁材的形成具有促进作用,然而当其分别增加至75℃和5.4 g时,壁材的平整度明显下降。三聚氰胺-甲醛树脂微胶囊成壁过程可分为3个阶段:预聚物分子缩聚形成大分子树脂颗粒,树脂颗粒从溶液中析出沉积在芯材表面,颗粒相互粘连形成连续壁材。

The micro glass beads with smooth surface and spherical profile were chosen as the core materials to prepare the melamine-formaldehyde microcapsules,in order to eliminate the influences of instability of common core materials on shell formation during in-situ polymerization. The effects of reaction time,reaction temperature and catalyst amount on the micro-morphologies of microcapsules were investigated by scanning electron microscope. The shell-forming mechanism was studied. The results showed that core surface was gradually covered by the particles with diameters less than 200 nm and the shell was formed. The shell formation was promoted by increasing of the reaction temperature and catalyst amount,but the flatness of the shell material was decreased significantly at 75 ℃ and 5.4 g,respectively. The shell-forming process for melamine-formaldehyde microcapsules could be divided into three stages. Firstly,the macromolecular resin particles were generated by polycondensation of prepolymer molecules. The resin particles were precipitated from the solution and deposited on the core surface. The particles adhered each other to form a continuous shell material