低摩尔比脲醛树脂掺杂支化聚合物体系研究

Study on the performance of low mole ratio urea-formaldehyde resin modified with branched polymer

【目的】脲醛树脂(UF)是生产人造板用最重要的一类胶黏剂,低摩尔比生产技术的推广使甲醛问题得到了有效控制,但树脂胶接及耐久性出现了急剧下降,为了协调甲醛与树脂性能之间的关系,本研究拟选取支化聚乙烯亚胺(HPEI)作为改性剂,利用其独特的结构特征,实现对低摩尔比脲醛树脂胶接性能的调控。【方法】设置了以HPEI聚合物添加量、添加方式为变量,考察在不同条件下对脲醛树脂体系胶接性能的影响,同时借助差示扫描量热仪(DSC)、傅里叶红外分析(FT-IR)、扫描电镜(SEM)等仪器分析手段对HPEI聚合物在树脂体系中的作用机制进行表征和分析。【结果】HPEI聚合物的引入可有效提升低摩尔比脲醛树脂的胶接强度,特别是耐水胶接强度,提升幅度最高可达65%。从经济角度考虑,HPEI聚合物的添加比例以1%为宜。对比HPEI聚合物的不同加入方式,在相同用量条件下,HPEI聚合物与脲醛树脂之间以共聚方式形成的体系,综合效果更加突出。通过FT-IR对不同树脂体系的结构组成分析发现,共聚合方式更加有利于HPEI与UF树脂体系之间化学层面交联反应的发生,而且从树脂固化特征参数的变化上也得到了印证。而根据对改性前后树脂的形貌特征分析也发现HPEI聚合物以共聚合方式加入到UF树脂体系中后,固化后树脂结构呈现出蓬松的层状组合特点,更有利于与木材之间形成良好的机械胶接,从而赋予树脂体系更加显著的胶接和耐久性。【结论】通过本试验的实施,HPEI聚合物可以用于低摩尔比脲醛树脂的增强改性剂,在树脂合成反应过程中添加1%质量比例的HPEI聚合物,可有效提升树脂的胶接及耐久性能,展现出了良好的发展前景。

【Objective】Urea-formaldehyde resin is an important adhesive in the production of man-made boards.With the application of low molar ratio UF resin,formaldehyde emission has been controlled effectively,but the resin bonding and durability have dropped sharply.In order to balance the relationship between the performance of low molar ratio UF resin and formaldehyde emission,branched polyethylenimine(HPEI)was selected as a modifier to optimize the performance of low molar ratio UF resin in this article.【Method】The addition amount and adding ways of HPEI polymer were set as variables,and their effects on the properties of the urea-formaldehyde resin system were evaluated.At the same time,the mechanisms of HPEI polymer in the UF resin system were characterized and analyzed by differential scanning calorimeter(DSC),Fourier infrared analysis(FTIR)and scanning electron microscope(SEM)analysis.【Result】The introduction of HPEI polymer can effectively improve the bonding strength of low molar ratio UF resin,especially the water-resistant bonding strength,and the improvement rate was up to 65%.From an economical point of view,the appropriate adding amount was 1%.Under the same dosage conditions,the system formed by co-polymerization between HPEI polymer and UF resin had a more outstanding comprehensive effect.Through FTIR analysis,it was found that the co-polymerization method was more conducive to the occurrence of chemical cross-linking between HPEI and UF resin systems,which was also confirmed by the change of resin curing characteristic parameters.According to the morphological characteristics of the resin before and after modification,it was found that the structure of the cured resin showed a fluffy layered combination characteristic after the addition of HPEI polymer into the UF resin system in the form of co-polymerization.This was beneficial to the formation of an excellent mechanical bonding among wood,thus the resin system had more significant bonding and durability.【Conclusion】Based on this test,HPEI polymer could be used as an enhancement modifier of low molar ratio UF resin,and the bonding strength and water resistance of low molar ratio UF resin can be effectively improved by adding 1%HPEI polymer during the process of resin synthesis.