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以高浓度甲醛和尿素制备的脲醛预缩液(UFC)为主要原料合成三聚氰胺-尿素-甲醛(MUF)树脂,选用3种不同固化剂(NH4Cl、HCOOH、NH4Cl+尿素)对MUF树脂的胶接性能进行评价和分析。结果表明:高浓度甲醛制备的MUF树脂交联度和缩聚度提高,树脂中的亚甲基桥键、醚键和羟甲基含量发生较大变化。以NH4Cl为固化剂时,湿状胶合板热稳定最好;以HCOOH为固化剂时,胶合板具有较高的干状强度,干状胶合板热稳定性最好,但耐久性极差;以NH4Cl+尿素为固化剂时,胶合板具有较高的干状和湿状强度,耐久性最好。
Melamine-urea-formaldehyde (MUF) resin was synthesized from urea-formaldehyde precondensate (UFC) prepared from high concentration of formaldehyde and urea. The adhesive properties of MUF resin with three different curing agents (NH4Cl, HCOOH and NH4Cl + urea) For evaluation and analysis. The results showed that the crosslinking degree and degree of polycondensation of MUF resin prepared by high concentration of formaldehyde increased, and the content of methylene bridge, ether bond and methylol in the resin changed greatly. When NH4Cl is used as the curing agent, the wet-type plywood has the best thermal stability. When HCOOH is used as the curing agent, the plywood has higher dry strength and the dry-type plywood has the best thermal stability, but the durability is very poor. The NH4Cl + Curing agent, the plywood has a high dry and wet strength, durability, the best.