Although polyamidoamine-epichlorohydrin (PAE)-modified soybean meal (SM) adhesives exhibit desired bond properties and technological applicability, their commercial application is still limited by the high cost of PAE resin. In this study, a formaldehyde-free crosslinking agent, melamine-urea-glyoxal (MUG) resin for SM adhesive, was developed based on investigations of the effects of melamine content and storage time on the structure and properties of MUG resin and MUG-modified SM adhesive. The test results confirmed that melamine could effectively copolymerize with glyoxal and urea to form an aldehyde-terminated MUG resin that was crosslinkable to soybean protein. The melamine content in MUG had important effects on the bond properties of the SM adhesive, attributed to the incorporation of aromatic triazine rings into the aliphatic urea-glyoxal chains and the greater reactivity and functionality of melamine than urea. However, the addition of melamine at more than 10% led to a shorter storage time of MUG resin and worse bond properties of MUG-modified SM adhesive. Owing to the further reactions of residual aldehyde and amino groups of MUG resin, the water resistance of the MUG-modified SM adhesive decreased with the storage time of the MUG resin. The allowable storage of the optimal MUG-10 resin was 3 weeks to ensure an acceptable bonding quality. Due to the much lower cost of MUG resin than PAE resin, it is beneficial for the wide commercial applications of formaldehyde-free SM adhesives in wood composites.

尽管聚酰胺胺-表氯醇（PAE）改性豆粕（SM）粘合剂表现出理想的粘合性能和技术适用性，但其商业应用仍受到PAE树脂成本高昂的限制。在这项研究中，基于三聚氰胺含量和储存时间对 MUG 树脂和 MUG 改性的结构和性能的影响的研究，开发了一种用于 SM 胶粘剂的无甲醛交联剂，三聚氰胺 - 脲 - 乙二醛 (MUG) 树脂。 SM粘合剂。测试结果证实，三聚氰胺可以有效地与乙二醛和尿素共聚，形成可与大豆蛋白交联的醛封端MUG树脂。MUG中的三聚氰胺含量对SM胶粘剂的粘接性能有重要影响，这归因于将芳族三嗪环并入脂肪族尿素-乙二醛链中，以及三聚氰胺比尿素具有更高的反应性和功能性。然而，三聚氰胺的添加量超过 10% 会导致 MUG 树脂的储存时间更短，MUG 改性的 SM 胶粘剂的粘合性能更差。由于MUG树脂残留醛基和氨基的进一步反应，MUG改性SM胶的耐水性随着MUG树脂储存时间的延长而降低。最佳 MUG-10 树脂的允许储存时间为 3 周，以确保可接受的粘合质量。由于 MUG 树脂的成本远低于 PAE 树脂，因此有利于无甲醛 SM 粘合剂在木材复合材料中的广泛商业应用。三聚氰胺的添加量超过10%会导致MUG树脂的储存时间更短，MUG改性的SM胶粘剂的粘合性能更差。由于MUG树脂残留醛基和氨基的进一步反应，MUG改性SM胶的耐水性随着MUG树脂储存时间的延长而降低。最佳 MUG-10 树脂的允许储存时间为 3 周，以确保可接受的粘合质量。由于 MUG 树脂的成本远低于 PAE 树脂，因此有利于无甲醛 SM 粘合剂在木材复合材料中的广泛商业应用。三聚氰胺的添加量超过10%会导致MUG树脂的储存时间更短，MUG改性的SM胶粘剂的粘合性能更差。由于MUG树脂残留醛基和氨基的进一步反应，MUG改性SM胶的耐水性随着MUG树脂储存时间的延长而降低。最佳 MUG-10 树脂的允许储存时间为 3 周，以确保可接受的粘合质量。由于 MUG 树脂的成本远低于 PAE 树脂，因此有利于无甲醛 SM 粘合剂在木材复合材料中的广泛商业应用。MUG改性SM胶的耐水性随MUG树脂储存时间的延长而降低。最佳 MUG-10 树脂的允许储存时间为 3 周，以确保可接受的粘合质量。由于 MUG 树脂的成本远低于 PAE 树脂，因此有利于无甲醛 SM 粘合剂在木材复合材料中的广泛商业应用。MUG改性SM胶的耐水性随MUG树脂储存时间的延长而降低。最佳 MUG-10 树脂的允许储存时间为 3 周，以确保可接受的粘合质量。由于 MUG 树脂的成本远低于 PAE 树脂，因此有利于无甲醛 SM 粘合剂在木材复合材料中的广泛商业应用。