聚乙烯醇缩醛树脂中残留甲醛含量的影响因素

Study on the Factors Affecting Free Formaldehyde in Poly(Vinyl formal) Resin

以尿素为甲醛捕捉剂,探讨了缩醛反应时间、反应温度、甲醛和聚乙烯醇的配比、盐酸、尿素、氢氧化钠等对聚乙烯醇缩甲醛溶液中残留甲醛含量的影响。结果表明,增加缩醛反应时间,利于降低产物游离甲醛含量。缩醛反应温度太低,产品中残留甲醛含量高。当反应温度由75℃增至88℃时,残留甲醛含量呈先快后慢的下降趋势变化。随投料中甲醛用量的提高,产物游离甲醛含量直线上升。当m(盐酸)∶m(PVA)由0.12增至0.29时,甲醛残余量则由0.247%降至0.216%。增加尿素用量,甲醛残余量先快速下降,然后缓慢下降。增加氢氧化钠用量,残留甲醛含量先缓慢增加,后快速增加。

With urea capturing formaldehyde, the factors affecting free formaldehyde, such as reaction time, reaction temperature, the ratio of formal to polyvinyl alcohol, hydrochloric acid, urea, sodium hydroxide, neutralization time, was inverstigated. The results showed that, prelonging reaction time, reducing formaldehyde content or increasing hydrochloric acid content can be benefited for decreasing free formaldehyde content（FFC）. When reaction temperature was too low, there was too much free formaldehyde in products. With reaction tempeture increased from 75 ℃ to 88 ℃, FFC decreased fastly first and then slowly, there was the same affectting trend for the urea on FFC as reaction tempeture. FFC increased first slowly and then fastly with the increment of sodium hydroxide content.