Abstract This study was conducted to prepare the microcapsules of polymeric 4-4 diphenyl methane diisocyanate (MpMDI) by interfacial polymerization using two different surfactants (Tween 40 and Gum Arabic) for the modification of urea-formaldehyde (UF) resins. MpMDI obtained by Tween 40 (TW-MpMDI) were spherical, smooth, and small diameter, while those prepared by Gum Arabic (GA-MpMDI) were irregular, rough surface, and larger diameter. Attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectra of two types of MpMDIs confirmed the successful microencapsulation of pMDI by detecting the isocyanate (N C O) groups after rupturing the shell of MpMDIs. As the MpMDI content in UF resins increased, the non-volatile solids content, pH, gelation time, viscosity, and exothermic peak temperature of UF/MpMDI adhesives slightly increased. Plywood bonded with UF/MpMDI adhesives had 15% higher tensile shear strength (TSS) and 30% higher modulus of rupture (MOR) than those of the plywood bonded with neat UF resins owing to the formation of urethane (HN-(C O)–O-R) bonds. In particular, plywood bonded with UF/TW-MpMDI had higher TSS and MOR values than those bonded with UF/GA-MpMDI adhesive. Regardless of the surfactant types, the formaldehyde emission decreased about 54% with 5% MpMDI addition into UF resins. These results and statistical analysis revealed that 1% TW-MpMDI addition into UF resins provided a proper balance between good adhesion and low formaldehyde emission for plywood.

中文翻译：

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聚异氰酸酯微胶囊化改性脲醛树脂

摘要 本研究使用两种不同的表面活性剂（吐温 40 和阿拉伯胶）通过界面聚合制备聚合 4-4 二苯基甲烷二异氰酸酯 (MpMDI) 微胶囊，用于改性脲甲醛 (UF) 树脂。Tween 40制备的MpMDI（TW-MpMDI）为球形、光滑、直径小，而阿拉伯胶制备的MpMDI（GA-MpMDI）则不规则、表面粗糙、直径较大。两种类型的 MpMDI 的衰减全反射-傅立叶变换红外 (ATR-FTIR) 光谱通过检测 MpMDI 外壳破裂后的异氰酸酯 (NCO) 基团，证实了 pMDI 的成功微囊化。随着UF树脂中MpMDI含量的增加，UF/MpMDI粘合剂的非挥发性固体含量、pH值、凝胶时间、粘度和放热峰温度略有增加。由于形成了氨基甲酸乙酯 (HN-(CO)–或）债券。特别是，用 UF/TW-MpMDI 粘合的胶合板比用 UF/GA-MpMDI 粘合剂粘合的胶合板具有更高的 TSS 和 MOR 值。无论表面活性剂类型如何，在超滤树脂中加入 5% MpMDI 后，甲醛释放量降低了约 54%。这些结果和统计分析表明，向 UF 树脂中添加 1% TW-MpMDI 为胶合板提供了良好粘合性和低甲醛释放量之间的适当平衡。