聚氨酯包膜控释尿素制备工艺与养分释放特性研究

Study of Preparation Technology and Nutrient Release Characteristics of Polyurethane Coated Controlled Release Urea

4,4'-二苯基甲烷二异氰酸酯(MDI)与植物油多元醇均匀喷涂在流化状态的尿素颗粒表面并发生化学反应,形成聚氨酯膜层。以侧喷流化床包膜工艺为基础,通过研究包膜量、反应温度、反应物比例等不同工艺条件下包膜尿素的养分释放性能,获得的生产聚氨酯包膜尿素的最佳工艺条件为反应温度75℃、MDI与植物油质量比1.0:1.0、反应时间20 min、催化剂用量0.40%(质量分数)、包膜比率为4.0%(质量分数),此包膜控释尿素的养分释放周期可达70 d。

4,4＇-diphenyl methane diisocyanate （MDI） and vegetable oil polyol are evenly sprayed on urea granule surface in fluidization state and chemical reaction happens, forming polyurethane film. Based on side-spray fluidized bed coating process, through research on coated urea nutrient release characteristics under different process conditions, such as coating quantity, reaction temperature, reactant ratio, etc., the optimum process conditions for production of polyurethane coated urea obtained are ： reaction temperature is 75 ℃, mass ratio of MDI to vegetable oil is 1.0 ： 1.0, reaction time is 20 min, catalyst consumption is 0.4% （mass fraction ） , the nutrient release period of coated release controlled urea with coating ratio 4.0% （mass fraction） can reach 70 d.