摘要
研究了脲醛树脂合成过程中抑制游离甲醛的方法,讨论了合成工艺的优化以及单宁酸和可溶性碱木质素作为降醛剂的效果。结果表明:优化后的合成工艺为甲醛与尿素的物质的量比为1.2∶1,缩聚反应阶段温度和p H值分别为95℃和5.0,三聚氰胺用量为尿素与甲醛总质量的2%,聚乙烯醇用量为尿素质量的1%。采用该工艺条件可使的产品中游离甲醛的量降到0.18%,黏度为16.2 s,固体质量分数为52.96%,储存时间大于45 d。采用单宁酸用量为尿素质量的2%时,产品中游离甲醛量为0.09%,固体质量分数为53.44%,黏度为16.9 s;可溶性碱木质素用量为尿素质量的5%时,游离甲醛的量为0.15%,其他指标与添加单宁酸的样品相似。
The methods of inhibiting free formaldehyde in the synthesis of urea-formaldehyde resins are investigated. The optimization of synthesis process and the effects of tannic acid and water-soluble alkali lignin as formaldehyde-reducing agents are discussed. The results show that the optimum conditions are the molar ratio of formaldehyde to urea 1. 2∶ 1,the temperature and p H value in condensation reaction 95 ℃ and 5. 0,the dosage of melamine 2 % of the total mass of urea and formaldehyde and the dosage of polyvinyl alcohol 1 % of the urea mass. The content of free formaldehyde in the product obtained under the optimum conditions can be reduced to 0. 18 % with the viscosity of 16. 2 s and solid content of 52. 96 %. And the storage time is more than45 d. When the dosage of tannic acid is 2 % of urea,the content of formaldehyde in the product can be further reduced to 0. 09% with the solid content of 53. 44 % and viscosity of 16. 9 s. The content of free formaldehyde is 0. 15 % when the dosage of soluble alkali lignin is 5 % of urea and the other characteristics are similar to the sample with addition of tannic acid.
出处
《生物质化学工程》
CAS
北大核心
2017年第1期20-26,共7页
Biomass Chemical Engineering
基金
国家自然科学基金资助项目(31370574,31300494)
湖北省教育厅创新团队项目(12053)
关键词
脲醛树脂
游离甲醛
降醛剂
单宁酸
木质素
urea-formaldehyde resin
free formaldehyde
formaldehyde-reducing agent
tannic acid
lignin
