Abstract The weak bonding strength and poor water resistance of soy protein-based adhesive have limited its application as a non-formaldehyde adhesive in wood manufacturing industry. In this work, a novel soy protein-based adhesive was prepared by introducing a tailor-made crosslinker with multiple epoxy groups and flexible long chains without any solvent or catalyst via a one-pot strategy. The multiple epoxy groups could react with the hydrophilic groups (hydroxyl and amino) on the soy protein molecules to construct densely crosslinking networks, which was proved by the sol-gel results. The crosslinking networks were beneficial to enhancing the bonding strength and water resistance of the adhesive. Consequently, the dry bonding strength and the wet bonding strength were increased from 1.11 MPa and 0.22 MPa to 2.79 MPa and 1.12 MPa, respectively, marking increments of 151% and 409% when compared to the pristine soy protein-based adhesive. The bonding strength was beyond the standard of type II plywood (≥0.7 MPa, GB/T17657−2013). Furthermore, the flexible long chains of the crosslinker was also conductive to improving the toughness of the adhesive. Therefore, this work may open a feasible way to produce non-formaldehyde adhesives with superior bonding strength and water resistance, and thus broadening the application of soy protein.

中文翻译：

---

通过设计密集的交联网络，大豆蛋白基粘合剂具有优异的粘合强度和耐水性

摘要 大豆蛋白基胶粘剂粘结强度弱、耐水性差，限制了其作为无甲醛胶粘剂在木材制造业中的应用。在这项工作中，通过一锅法在不使用任何溶剂或催化剂的情况下引入具有多个环氧基团和柔性长链的定制交联剂，制备了一种新型的大豆蛋白基粘合剂。多个环氧基团可以与大豆蛋白分子上的亲水基团（羟基和氨基）反应，构建致密的交联网络，溶胶-凝胶结果证明了这一点。交联网络有利于提高粘合剂的粘合强度和耐水性。因此，干粘合强度和湿粘合强度分别从 1.11 MPa 和 0.22 MPa 增加到 2.79 MPa 和 1.12 MPa，与原始的基于大豆蛋白的粘合剂相比，标记增量为 151% 和 409%。粘接强度超过Ⅱ类胶合板标准（≥0.7 MPa，GB/T17657-2013）。此外，交联剂的柔性长链也有助于提高粘合剂的韧性。因此，这项工作可能为生产具有优异粘合强度和耐水性的无甲醛粘合剂开辟了一条可行的途径，从而拓宽了大豆蛋白的应用范围。