【摘要】 脲醛树脂是应用于木材工业中一种重要的胶黏剂,目前合成脲醛树脂的工艺主要有弱碱~弱酸~弱碱和强酸~弱酸~弱碱中低温两种工艺,本文就脲醛树脂的两种合成机理和两种合成工艺进行了探讨,并在大量实验的基础上对两种工艺做了比较,研究结果表明:工艺路线1(弱碱~弱酸~弱碱)合成的UF树脂中游离甲醛含量明显高于工艺路线2(强酸~弱酸~弱碱中低温)合成的树脂中游离甲醛含量;同时工艺路线2合成的UF树脂中的羟甲基含量高于用工艺路线1合成的UF树脂。更多还原

【Abstract】 Urea-formaldehyde(UF) resins are widely used as one of the most important adhesives in the wood industry.So far there are two main processes of synthesizing UF resins:(Ⅰ)alkalescence～subacidity～alkalescence;and (Ⅱ) strong acidity～subacidity～alkalescence with medium to low temperature.In this paper,the synthesis mechanisms and methods of these two processes are studied,and also the two processes are compared based on many experiments.The results indicate that the content of free formaldehyde in the urea-formaldehyde resins synthesized by processⅠ(alkalescence～subacidity～alkalescence) are much more than that by process Ⅱ(strong acidity～acidity～alkalescence with medium to low temperature),but the content of hydroxymethyl is just the opposite.更多还原