降低脲醛树脂游离甲醛含量的探讨

Study on reducing content of free formaldehyde of UF

通过对脲醛树脂反应机理的研究,,对尿素与甲醛的摩尔比、尿素加料工艺、pH值控制和添加剂的使用提出新见解。当摩尔比采用1:1.1～1.3,尿素分三次添加,缩聚反应的pH值控制在4.4～5.0,用聚乙烯醇作添加剂,脲醛树脂胶的甲醛含量可降至0.8％以下,明显低于国家标准小于2.5％的要求,胶液初黏力强、柔韧性好,各项指标均符合HG—1233—79标准。

New ideas on molar ratio of urea with formaldehydes, process of reinforced urea, pH control, and usage of additive are presented by means of study on reaction mechanism of UF. The molar ratio was adopted 1:1.1-1.3, urea was reinforced three times, pH of condensation polymerization was controled at 4.4 - 5.0,PVA was used on additive. The content of free formaldehyde in the UF glue may be reduced below 0.8% , much less than 2.5% of the National Standard. Its initial strength was higher and pliable with tough were excellent. Every index is accorded with the Standard HG-1233-79.