聚氨酯包膜尿素的制备

Preparation of Controlled-Release Polyurethane Coated Urea

用异氰酸酯与聚氧化丙烯二醇（PPG）合成聚氨酯,再以其包裹尿素制成聚氨酯包膜尿素。采用比色法绘制聚氨酯包膜尿素的缓释曲线,讨论了异氰酸酯与羟基摩尔比（NCO/OH）、包膜率、反应方式、异氰酸酯、PPG分子量对包膜尿素缓释性能的影响。结果发现,以丙酮为溶剂,NCO/OH为1.1,在50~60℃的水浴温度下,PPG-3000先与MDI反应1 h、再与尿素反应2 h,得到的包膜率为5%的聚氨酯包膜尿素满足欧洲标准委员会的缓释肥料标准。

Isocyanate and polyethylene oxide propylene glycol（PPG） were used to synthesize polyurethane coating material and polyurethane coated urea was obtained.The controlled-release curves of polyurethane coated urea was obtained by the colorimetry,and the influences of molar ratio of NCO/OH,coating rate,reaction mode,isocyanate and PPG molecular weight on the controlled-release performance of polyurethane coated urea were discussed.It was proved that 5% polyurethane coated urea met the requirement for controlled-release fertilizer according to Europe Standard,which was prepared by PPG-3000 reacting with MDI for 1 h first and then reacting with urea for 2 h in acetone at 50~60℃ with NCO/OH of 1.1.