摘要： 采用甲苯二异氰酸酯(TDI)、三羟甲基丙烷(TMP)、二羟甲基丙酸(DMPA)为原料，2-甲基咪唑为封闭剂，三乙胺为中和剂制备了水分散封闭异氰酸酯(WBI)乳液，考察了中和剂和 Zeta电位(ζ-电位)对 WBI乳液稳定性的影响，探讨了乳液耐电解质能力及其温敏特性对其解封温度及双组分聚氨酯漆膜性能的影响。实验结果表明:用三乙胺作为中和剂时，乳液粒径较小，稳定性及贮存稳定性均较好，最佳中和度为 10%。随 DMPA用量的增加，乳液的 ζ电位绝对值增大，乳液粒径减小、耐电解质能力增强，乳液的稳定性提高。乳液的 Zeta电位及粒径受温度影响较小，说明乳液较为稳定。DMPA用量为 20% ~25%(摩尔分数)较适宜。差示扫描量热法(DSC)分析表征其解封温度为125.6~138.1°C，应用表明此类 WBI作为固化剂可以赋予涂料较好的耐水性、耐醇性、硬度及耐冲击性。

关键词: 水分散封闭多异氰酸酯, Zeta电位, 稳定性, 二羟甲基丙酸, 粒径

Abstract: Waterborne blocked isocyanate emulsion (WBI) was synthesized with toluene 2, 4-diisocyanate(TDI), trimethylolpropane(TMP), dimethylol propionic acid(DMPA)as the reactants and 2-meth-ylimidazole(2-MI) as blocked agents and triethylamine as nentralizer. The influence of neutralizer and Zeta potential on stability of WBI emulsion was studied. The hydrolyte resistance and temperature dependence of emulsion and unblocking temperature of WBI and properties of two-component polyurethane film were discussed. The results showed that when triethylamine(TEA)was used as neutralizer the emulsion provided good stability and storage stability due to the small particle size e. When the neutralization was up to 100%, the stability of emulsion was the best. With the increase of DMPA the stability of the emulsion was improved. The Zeta potential and particle sized were less influenced by temperature. Suitable mole fraction of DMPA is 20%~25%. The unblocking temperature was 125. 6 ℃ to 137. 8 ℃ by DSC test. The WBI hardness and impact could be used as curing agent to provide better water resistance, alcohol resistance poverties of coatings.

Key words: waterborne blocked isocyanate, Zeta potential, stability, dimethylol propionic acid, particle size