摘要
讨论了可用于制备低甲醛释放刨花板与胶合板的脲醛 (UF)树脂制备参数。该UF树脂制备经过 4个pH值 ( 1 .5 ,9.0 ,4 .5 ,8.0 )阶段 ,最后阶段加入尿素的量对UF树脂游离甲醛的含量有着重要的影响。在弱酸阶段随着甲醛与尿素摩尔比和 pH值的下降 ,通过亚甲基键连接的尿素和高分子质量树脂含量增加 ,而通过亚甲基醚键连接的尿素的含量下降 ;在碱性条件下甲醛与尿素摩尔比相同的树脂 ,较高的 pH值可以降低游离甲醛的含量和释放量。当添加 2 %～ 5 %的胶粘剂时 ,可提高低摩尔比的UF树脂对木材的胶合性能。当甲醛与尿素摩尔比达到 1∶1时 。
Parameters in resin manufacture to produce formaldehyde-urea(UF)resins capable of producing low formaldehyde emission particleboards and plywoods were presented and discussed.UF resins were produced through four stages of different reaction pH values(1.5,9.0,4.5,8.0).Free formaldehyde contents of UF resins were affected most significantly by the amount of the added urea in the last stage.During the weak acid stage,methylene linkages in the polymeric resin increased and dimethylene ether linkages decreased as formaldehyde/urea molar ratio and pH decreased.While in the alkaline pH stage,under similar formaldehyde/urea ratio,free formaldehyde content and formaldehyde emission decreased with increase of reaction pH.Addition of 2%-5%(mass ratio)crosslinking agent improved wood adhesion of UF resin of low molar ratio.Formaldehyde emission reached E1(<10 mg/100 g)standard requirement when particleboard and plywood were made with UF resin when formaldehyde/urea molar ratio was lowered to 1∶1.
出处
《林产化学与工业》
EI
CAS
CSCD
2002年第2期39-42,共4页
Chemistry and Industry of Forest Products
