高温致活工业明胶木材胶黏剂的制备及应用

Preparation and Application of High Temperature Activated Industrial Gelatin Wood Adhesive

摘要:

以废弃皮革中提取的工业明胶为原料，甲乙酮肟制备的封闭型水性聚氨酯为交联剂，通过在高温热压条件下解封 出活性异氰酸酯基团，使其与明胶产生交联，合成出高温致活封闭型工业明胶木材胶黏剂。FT-IR和DSC结果表明：甲乙酮肟分子上的羟基与聚氨酯预聚体上的异氰酸酯基团发生缩聚反应，其最大解封温度在约126℃处。SEM观察到结果显示：胶黏剂经高温固化后表面更为光滑，说明明胶与封闭型水性聚氨酯组分间的相容性得到了提高。应用试验测试结果表明：当封闭型水性聚氨酯的用量为占明胶水溶液质量的20%时，胶黏剂的湿剪切强度高达0.97MPa，满足国家Ⅱ类胶合板的使用要求，且最佳的热压工艺条件是热压温度150℃、热压时间4min，涂胶量300g/m2。 关键词：工业明胶，封闭型水性聚氨酯，木材胶黏剂，剪切强度

Abstract:

A high temperature activated industrial gelatin wood adhesive was synthesized via the reaction between gelatin and isocynate groups released by crosslinking agent, using industrial gelatin extracted from waste leather as raw materials and blocked waterborne polyurethane prepared by methyl ethyl ketoxime as crosslinking agent. FT-IR and DSC showed that the hydroxyl group on the methyl ethyl ketone oxime molecule was polycondensed with the isocyanate group on the polyurethane prepolymer, and the maximum unblocking temperature was about 126 °C. SEM showed that the surface of the adhesive was smoother after curing at high temperature, indicating that the compatibility between gelatin and the blocked waterborne polyurethane component was improved. The application test results show that the wet shear strength of adhesive is up to 0.97MPawhen the content of the blocked waterborne polyurethane is 20%of the mass of gelatin aqueous solution, which meets the requirements of the national class II plywood. The optimum hot pressing process conditions are a hot pressing temperature of 150℃, a hot pressing time of 4 min, and a coating amount of 300 g/m2. Keywords: industrial gelatin, blocked waterborne polyurethane, wood adhesive, shear strength Foundation item: National Natural Science Foundation of China(No. 21776169)