E_1级MDF用三聚氰胺改性脲醛树脂的定量^(13)C-NMR结构研究

The Quantitative ^(13)C-NMR Analysis of Melamine-modified UF Resin for E_1 Type MDF

采用13C-核磁共振定量分析了由选定碱-酸-碱工艺所合成的E1级MDF用三聚氰胺改性脲醛树脂。结果表明:在初始碱性阶段有70％的甲醛分子转化成了羟甲基脲,25％的甲醛分子转化成了亚甲基醚键。三聚氰胺全部发生羟甲基化,65％的羟甲基三聚氰胺缩聚成亚甲基醚键的结构。亚甲基醚键在最后的碱性保温阶段发生分解。三聚氰胺对缩聚反应的参与提高了亚甲基键的含量。

The melamine-modified urea-formaldehyde resin （MUF） for E1 type MDF was quantitatively examined using the ^13C-NMR spectroscopy. It was proved that 70% of formaldehyde molecule transformed into hydroxymethylureas and another 25% of formaldehyde molecule formed methyleneether bond in the initial alkaline reaction stage. All the melamine was hydroxymethyled,and 65G of hydroxymethylmelamine was condensated into methylene-ether bonded melamine. Methylene-ether groups decomposed in the last alkaline thermal imsulating stage. The quantity of methylene bond was raised with the participation of melamine in condensation reaction