论文部分内容阅读
采用“碱-酸-碱”传统合成工艺、n(F)∶n(U)比例降至0.96∶1、尿素分3次投料、调节三聚氰胺的加入量以及加入方式、加入聚乙烯醇(PVA)等其他助剂、控制缩聚温度为90℃和缩聚阶段的pH为4.8左右等,制备MDF(中密度纤维板)用MUF(三聚氰胺-尿素-甲醛共缩聚树脂)胶粘剂。研究结果表明:MUF的游离甲醛含量低于0.2%、固含量约53%,并且其固化时间和黏度等均适用于MDF的制备;当w(总三聚氰胺)=4%、w(前期三聚氰胺)=2%时,选择适宜的热压工艺,所得MDF的性能[如内结合强度(IB)、静曲强度(MOR)、弹性模量(MOE)和吸水厚度膨胀率(TS)等]和甲醛释放量(7.94 mg/100 g)均达到GB/T 11718—2009标准要求。
The ratio of n (F): n (U) was reduced to 0.96:1 by using “Alkali-Acid-Alkali” conventional synthesis process. The urea was fed in three times to adjust the amount of melamine added and the addition method. PVA) and other additives to control the polycondensation temperature of 90 ° C and the polycondensation stage of the pH of about 4.8, etc., to prepare MDF (MDF) with MUF (melamine - urea - formaldehyde co-condensation resin) adhesive. The results showed that the free formaldehyde content of MUF was less than 0.2% and the solid content was about 53%. The curing time and viscosity of MUF were suitable for the preparation of MDF. When w (total melamine) = 4%, w (pre-melamine) = 2%, the suitable hot pressing technology, the properties of MDF [such as internal bond strength (IB), MOR [MOR], elastic modulus (MOE) The amount (7.94 mg / 100 g) met the requirements of GB / T 11718-2009 standard.