Abstract: Biurea was successfully synthesized from ketazine，urea and water by a one-step process. The structure and physical properties of the produced biurea was confirmed by IR spectrometry，TG-DTA and DSC. The reaction conditions were investigated including the ratio of ketazine to urea，the urea concentration，reaction time and the recycling of the mother liquor. The prepared biurea was used to the synthesis of azo-diformamide，and the obtained product can achieve the excellent product quality as stated by HG/T 2097—2008 standard.

摘要： 以自制的丁酮连氮为原料和尿素、水一步反应制备了联二脲。用红外光谱（FTIR）、差热-热失重分析（TG-DTA），差示扫描量热法（DSC）对合成的联二脲进行了结构表征和物性测试。考察了丁酮连氮与尿素投料比例、反应时间、尿素浓度、母液循环使用对联二脲收率的影响。用此法得到的联二脲合成偶氮二甲酰胺发泡剂，其物性能够达到化工行业标准HG/T 2097—2008的优等品指标。