We examine the nature of the chemical reactions taking place in a waterborne two-component polyurethane formulation consisting of an acrylic polyol latex and a hydrophilically modified polyisocyanate (hmPIC) based on the trimer of hexamethylene diisocyanate. The hmPIC was diluted with 30 wt.% of an organic solvent to reduce its viscosity and formed small (~20 nm) droplets when dispersed in water. In mixtures of the polyol and hmPIC, we monitored the rate of NCO group disappearance in the dispersed state by FTIR and showed that it varied with the choice of organic solvent. We developed a method based upon ¹⁹F NMR to distinguish the reaction of the NCO groups with OH groups from the polyol from its reaction with water. FTIR measurements on films formed from these dispersions showed how the disappearance of NCO groups depended on relative humidity. In a more semi-quantitative way, these measurements indicated the relative extent of urethane versus urea formation in these model coatings.

中文翻译：

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监测分散体和成膜过程中水性 2 包聚氨酯涂料的反应动力学

我们研究了水性双组分聚氨酯配方中发生的化学反应的性质，该配方由丙烯酸多元醇胶乳和基于六亚甲基二异氰酸酯三聚体的亲水改性多异氰酸酯 (hmPIC) 组成。hmPIC 用 30 wt.% 的有机溶剂稀释以降低其粘度，并在分散在水中时形成小的 (~20 nm) 液滴。在多元醇和 hmPIC 的混合物中，我们通过 FTIR 监测了 NCO 基团在分散状态下消失的速率，结果表明它随有机溶剂的选择而变化。我们开发了一种基于¹⁹F NMR 以区分 NCO 基团与 OH 基团的反应与多元醇与水的反应。对由这些分散体形成的薄膜的 FTIR 测量显示 NCO 基团的消失如何取决于相对湿度。以更半定量的方式，这些测量表明这些模型涂层中氨基甲酸酯与尿素形成的相对程度。