GHD室温自交联乳液的聚合及贮存稳定性

采用半连续种子乳液聚合技术合成了含甲基丙烯酸缩水甘油酯(GMA)、甲基丙烯酸羟乙酯(HEMA)和甲基丙烯酸二甲氨基乙酯(DMAEMA)的室温自交联乳液(GHD).实验结果表明,在甲基丙烯酸甲酯(MMA)-丙烯酸丁酯(BA)-GMA种子乳液存在下,聚合温度升高,聚合过程稳定性下降,但乳液的贮存稳定性提高;乳化单体滴加速度加快,种子聚合物的玻璃化温度升高,可减少聚合过程的交联凝聚作用,提高聚合过程的稳定性;而HEMA和DMAEMA用量增加对聚合过程的稳定性没有明显影响,但使乳液的贮存稳定性下降.官能团间的交联凝聚作用可能是影响室温自交联乳液聚合及贮存过程稳定性的关键因素.

Stability of the GHD Latex Crosslinkable at Ambient Temperature

The GHD latex containing glycidyl methacrylate(GMA), hydroxyl methacrylate(HEMA) and dimethylaminoethyl methacrylate(DMAEMA), which is crosslinkable at ambient temperature, was synthesized. In the presence of the seed latex of methyl methacrylate(MMA)-butyl acrylate(BA)-GMA, the effects of the polymerization technology and the recipes on the process stability of the emulsion copolymerization(PSEC) of MMA-BA-HEMA-DMAEMA and the shelf life of the crosslinkable latex obtained were studied. PSEC and the shelf life are improved as more emulsifier is used. When the polymerization temperature is raised, PSEC becomes worse because the crosslinking coagulation is increased, but the shelf life of the latex becomes longer because of the smaller particles and the lower surface tension. Raising T_g of the seed polymer can depress the crosslinking coagulation during the copolymerization and improve PSEC. Increasing the content of HEMA and DMAEMA has little influence on PSEC but it reduces the shelf life of the latex. When the functional group is separated through the particle designing, the latex with acceptable shelf life is obtained. It was deduced that the crosslinking coagulation may be the key factor which determined the PSEC and the shelf life of the latex crosslinked at ambient temperature.