聚氨酯交联改性工业明胶木材胶黏剂的制备与性能

Preparation and Properties of Industrial Gelatin Wood Adhesive Modified by Polyurethane

首先以异佛尔酮二异氰酸酯(IPDI)、聚四氢呋喃(PTMG)和2,4-二羟基苯甲醛(DBA)为原料制备了水性聚氨酯(DBA-WPU),再以此为交联剂,通过其分子链上的醛基与废弃皮革中提取的工业明胶(INGE)的氨基发生Schiff碱交联反应制得木材胶黏剂INGE/DBA-WPU。紫外光谱(UV-vis)、傅里叶变换红外光谱(FT-IR)和核磁分析(~1H-NMR)表明成功地将DBA引入到水性聚氨酯分子主链上,利用DBA分子链上的羟基与聚氨酯预聚体上的异氰酸酯基反应制备DBA-WPU交联剂。通过FT-IR、X射线衍射(XRD)、接触角、热重分析(TGA)和湿剪切强度对INGE/DBA-WPU黏合剂进行性能检测和结构表征。结果表明,DBA-WPU与INGE发生交联反应,使得胶黏剂的接触角和热稳定性提高。应用试验结果表明,当DBA-WPU用量为30%时,胶黏剂的湿剪切强度高达1.1 MPa,满足GB/T 9846.3-2004中Ⅱ类胶合板的使用要求(≥0.7 MPa),表明引入DBA-WPU可以提高INGE木材黏合剂的耐水性。

The waterborne polyurethane was prepared from isophorone diisocyanate(IPDI), polytetrahydrofuran(PTMG), and 2,4-dihydroxybenzaldehyde(DBA), and the prepared waterborne polyurethane was used as crosslinking agent. A wood adhesive was prepared by Schiff base reaction between the aldehyde groups on the waterborne polyurethane molecular chains and the amino groups of industrial gelatin(INGE) extracted from waste leather. UV-vis, ~1H-NMR and FT-IR show that DBA-WPU was successfully synthesized by reacting hydroxyl groups of the DBA molecular chains with isocyanate groups of the polyurethane prepolymer. The performance testing and structural characterization of INGE/DBA-WPU adhesives were tested by FT-IR, XRD, contact angle, TGA and wet shear strength. The results show that the crosslinking reaction between the DBA-WPU and INGE can increase the contact angle and thermal stability of the adhesives. The application test results show that the wet shear strength of the adhesives reaches 1.1 MPa when the amount of polyurethane is 30%, which meets the requirements of GB/T 9846.3-2004(≥0.7 MPa), indicating the introduction of DBA-WPU can improve the water resistance of INGE wood adhesives.