麦芽糖改性脲醛树脂的合成与热性能研究

Synthesis and Thermal Properties of Maltose Modified Urea-Formaldehyde Resin

以尿素(U)、甲醛(F)、麦芽糖(Ma)为主要原料,用碱(T_(1))—酸(T_(2))—碱(T_(3))工艺合成麦芽糖改性脲醛树脂(MaUF)。探讨麦芽糖添加量和添加时刻对MaUF树脂的影响,并采用傅立叶红外光谱(FT-IR)和热分析方法(DSC、TG、DTG)对MaUF树脂性能进行分析表征。结果表明:随麦芽糖添加量增加,T_(2)阶段的MaUF树脂湿状胶合强度先升高后降低,游离甲醛含量降低,固体含量升高;采用优化合成工艺:n(U)∶n(F)=1∶1.3、麦芽糖添加量为18%,胶合性能与游离甲醛含量达到国家标准要求。FT-IR表明:1133 cm^(−1)处醚键吸收峰增强,麦芽糖参与树脂反应,且以醚键相连。DSC与TG、DTG分析表明:麦芽糖使树脂的起始温度、峰值温度、终止温度升高,放出热量增加,树脂固化变难;麦芽糖可能与甲醛或羟甲基脲发生反应,MaUF树脂热稳定性较差。

In this study,urea(U),formaldehyde(F)and maltose(Ma)were used as main raw materials to synthesize maltose modified urea-formaldehyde resin(MaUF)by the process of"alkali(T_(1))-acid(T_(2))-alkali(T_(3))".The effects of maltose addition amount and time on the properties of MaUF resin were studied and characterized(DSC,TG and DTG).The results showed that with the increase of maltose content,the wet bonding strength of MaUF resin in T_(2) stage first increased and then decreased,the free formaldehyde content decreased and the solid content increased.The optimal synthesis process was n(U)∶n(F)=1∶1.3,maltose content was 18%,and bonding property and free formaldehyde content could meet the requirements of national standards.FT-IR showed that the absorption peak of ether bond at 1133 cm^(−1) was enhanced,and maltose participated in the resin reaction and was linked by ether bond.DSC analysis showed that maltose increased the initial temperature,peak temperature and end temperature of the resin,and increased the heat release,which made it difficult to cure the resin.TG and DTG curve analysis showed that maltose may react with formaldehyde or hydroxymethylurea,and the thermal stability of MaUF resin was poor.