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首页> 外文期刊>Journal of Wood Chemistry and Technology >Formaldehyde Resin Cure in Medium Density Fiber board: Resin Extractability and Fiber Effects
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Formaldehyde Resin Cure in Medium Density Fiber board: Resin Extractability and Fiber Effects

机译：中密度纤维板中的甲醛树脂固化：树脂的可萃取性和纤维效应

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摘要

The degree of resin cure achievable in urea formaldehyde (UF) resin is known to influence the hydrolytic stability of UF resin. In the current study, a significant difference in water extractable resin components has been observed between cured pure resin and that from medium density fiberboard (MDF) panels. Results show some 50 to 70% of resin components may he removed on water extraction from resinated MDF fiber and panel samples. In contrast, cured pure UF resins have only a small fraction of resin mass extractable into water with nitrogen-containing components remaining incorporated into the cured resin. The relatively high resin mass losses from panel material together with loss of nitrogen-containing components suggest not only free urea, but urea-methylene species are labile and readily extractable into water. Wax contributes to differing panel extractability when pressed at either 100 or 160℃, whereas panel resin loading has a significant effect on extractable resin components. A lower resin loading led to relatively greater resin extractability, which was corroborated by the extractability of resin-fiber mixtures up to 50% resin content. An assessment of extracted panel residues suggests a relative decrease of urea and urea-formaldehyde condensation products after water extraction. With UF resin highly mobile on fiber during MDF manufacture, the results suggest resin components may separate, leading to their incomplete incorporation into a cured, cross-linked UF resin matrix, with an implication that resin cure on fiber may not be complete compared to that found with pure resin.
机译：已知在脲甲醛（UF）树脂中可达到的树脂固化程度会影响UF树脂的水解稳定性。在当前的研究中，已观察到固化的纯树脂与中密度纤维板（MDF）板之间的可提取水的树脂成分存在显着差异。结果表明，从树脂化的MDF纤维和面板样品中提取水后，可能会去除约50％至70％的树脂成分。相比之下，固化的纯UF树脂中只有少量的树脂块可萃取到水中，而含氮组分仍然掺入固化的树脂中。来自面板材料的较高的树脂质量损失以及含氮组分的损失不仅表明游离尿素，而且尿素-亚甲基物质不稳定并且易于提取到水中。在100或160℃下压蜡时，蜡会导致不同的面板可萃取性，而面板树脂的负载量对可萃取树脂成分有显着影响。较低的树脂负载量导致相对较高的树脂可萃取性，这可通过树脂-纤维混合物的可萃取性达到50％的树脂含量得到证实。对提取的面板残留物的评估表明，水提取后尿素和尿素-甲醛缩合产物相对减少。由于UF树脂在MDF制造过程中在纤维上具有很高的流动性，因此结果表明，树脂成分可能会分离，导致它们不完全掺入固化的交联UF树脂基体中，这意味着与纤维相比，树脂在纤维上的固化可能不完全用纯树脂发现。

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