反应原料用量对MUF共缩聚树脂分子量分布的影响

三聚氰胺改性脲醛树脂,是业界普遍采用的脲醛树脂改性方法之一。三聚氰胺的加入可以有效改善脲醛树脂的耐水、耐候性,降低游离甲醛含量等。然而,三聚氰胺能否有效参与到脲醛树脂反应体系当中,形成有效的共缩聚成分,对树脂的应用性能更为关键。基于此,文中设置了在终反应摩尔比以及第1阶段摩尔比保持不变的条件下,通过改变反应原料用量,即三聚氰胺与尿素的用量,合成了一系列三聚氰胺-尿素-甲醛(MUF)共缩聚树脂,利用电喷雾电离质谱仪(ESI-MS)对合成的不同MUF共缩聚树脂的分子量分布情况进行了表征。比较不同样品所测图谱,结果表明,在合成反应过程中,通过改变三聚氰胺(M)与尿素(U)的用量对MUF共缩聚树脂分子量的形成、分布及共缩聚成分有较大影响,当M用量占M与U总质量比例增加至40%时,MUF共缩聚树脂分子量的分布发生了质的改变,同时,共缩聚成分的比例也有明显增加。因此,可以认为,在该试验条件下,增加M的用量可以有效促进共缩聚反应的进程,同时,真正意义上的共缩聚树脂的形成,要求M的加入量至少应控制在40%。

The effect of reaction material content on the molecular distribution of MUF co-condensation resin

Urea-formaldehyde resin modified with melamine is a common method adopted widely in the industry. Melamine can effectively modify the water resistance and weather durability of urea-formaldehyde resin, and reduce the content of free formaldehyde. However, during the resin application, it is very important for melamine to take part in urea-formaldehyde resin reaction and form effective co-condensation composition or not. Based on above, a series of MUF resins are synthesized with different melamine and urea mass ratio under the same final F ∶( M+U) and the first stage F ∶( M1+U1 ) molar ratio condition. And the molecular distribution of different resins are represented by using electrospray ionization mass spectrometry ( ESI-MS) . By comparing figures of different samples, the results showed that different reaction material content has a great influence on the composition, molecular distribution and co-condensation content of co-condensation resin. And when the mass amount of melamine added to 40%, the molecular distribution of MUF resin changed qualitatively and co-condensation composition content also had significant increase. Therefore, under this experiment conditions, adding melamine content can effectively promote the co-condensation reaction, meanwhile, the formation of co-condensation resin requires melamine content at least about 40%.