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High-value utilization of hydroxymethylated lignin in polyurethane adhesives.
International Journal of Biological Macromolecules ( IF 7.7 ) Pub Date : 2020-02-28 , DOI: 10.1016/j.ijbiomac.2020.02.321 Yinchen Chen 1 , Hui Zhang 2 , Zhaodong Zhu 2 , Shiyu Fu 1
International Journal of Biological Macromolecules ( IF 7.7 ) Pub Date : 2020-02-28 , DOI: 10.1016/j.ijbiomac.2020.02.321 Yinchen Chen 1 , Hui Zhang 2 , Zhaodong Zhu 2 , Shiyu Fu 1
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Lignin is a good candidate for the polymerization and chemical modification to prepare sustainable chemicals and materials, but a relatively low hydroxyl content becomes an obstacle for the preparation of lignin-based polyurethane (PU) adhesives. In order to improve its reactivity, the acetic acid lignin (AAL) was hydroxymethylated before copolymerized with isocyanate during the preparation of PU adhesives. The hydroxymethylation was carried out in an alkaline formaldehyde solution and it was found that 85 °C is the optimal temperature. On that condition, the free formaldehyde content of the corresponding product HL-6 was as low as 0.32%, while the hydroxymethyl was increased by 189.11% compared with original AAL and reached 2.92 mmol/g. In the polymerization of PU adhesives, the hydroxymethylated lignin with a higher aliphatic hydroxyl content formed a more compact three-dimensional urethane cross-linking network with isocyanate. The mechanical properties and thermal stability of the lignin-based PU adhesive were improved by 15-30 wt% in HL-6, and particularly the tensile strength was increased by 21-41 MPa, which indicated that the hydroxymethylation is an efficient way to enrich the hydroxyl in lignin, and the modified lignin is adequate to partially replace petroleum-based polyols for the preparation of PU adhesives with excellent properties.
中文翻译：
羟甲基化木质素在聚氨酯胶粘剂中的高价值利用。
木质素是用于聚合和化学改性以制备可持续的化学品和材料的良好候选者，但是相对较低的羟基含量成为制备木质素基聚氨酯（PU）粘合剂的障碍。为了提高其反应性，在制备PU粘合剂期间，先将乙酸木质素（AAL）羟甲基化，然后再与异氰酸酯共聚。在碱性甲醛溶液中进行羟甲基化，发现最适温度为85℃。在此条件下，相应产物HL-6的游离甲醛含量低至0.32％，而羟甲基与原始AAL相比增加了189.11％，达到2.92 mmol / g。在聚氨酯胶粘剂的聚合中，具有较高脂肪族羟基含量的羟甲基化木质素与异氰酸酯形成了更紧密的三维氨基甲酸酯交联网络。木质素基聚氨酯胶粘剂在HL-6中的机械性能和热稳定性提高了15-30 wt％，尤其是抗张强度提高了21-41 MPa，这表明羟甲基化是一种有效的富集方法木质素中的羟基，改性木质素足以部分替代石油基多元醇，以制备性能优异的PU胶粘剂。
更新日期：2020-03-02
中文翻译：
羟甲基化木质素在聚氨酯胶粘剂中的高价值利用。
木质素是用于聚合和化学改性以制备可持续的化学品和材料的良好候选者，但是相对较低的羟基含量成为制备木质素基聚氨酯（PU）粘合剂的障碍。为了提高其反应性，在制备PU粘合剂期间，先将乙酸木质素（AAL）羟甲基化，然后再与异氰酸酯共聚。在碱性甲醛溶液中进行羟甲基化，发现最适温度为85℃。在此条件下，相应产物HL-6的游离甲醛含量低至0.32％，而羟甲基与原始AAL相比增加了189.11％，达到2.92 mmol / g。在聚氨酯胶粘剂的聚合中，具有较高脂肪族羟基含量的羟甲基化木质素与异氰酸酯形成了更紧密的三维氨基甲酸酯交联网络。木质素基聚氨酯胶粘剂在HL-6中的机械性能和热稳定性提高了15-30 wt％，尤其是抗张强度提高了21-41 MPa，这表明羟甲基化是一种有效的富集方法木质素中的羟基，改性木质素足以部分替代石油基多元醇，以制备性能优异的PU胶粘剂。
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