双层和夹层包膜工艺对水基树脂包膜材料控释性能的影响

    Effect of double and triple layers coating technique on controlled release properties of waterbased resin coating material

    • 摘要: 为了优化水基树脂的包膜控释性能,该文以脂溶性树脂为配合包膜材料,利用底喷风动流化床制造多层包膜控释尿素,并通过包膜控释尿素养分释放率的测定评价双层和夹层包膜工艺对水基树脂包膜材料控释性能的影响。研究结果表明:两种工艺相比,夹层包膜工艺能显著延长包膜控释尿素的肥效期,其肥效期是双层包膜工艺的5倍。在夹层包膜工艺中,内保护层厚度在5~15 g/m2的范围内对包膜控释尿素的肥效期无明显影响,50 g/m2水基树脂控释层和10?g/m2脂溶性树脂外保护层夹层控释尿素的肥效期均约为260 d。但是,夹层包膜控释尿素的养分释放模式与内保护层厚度有关,内保护层厚度达到10 g/m2以上时,养分释放模式由抛物线型变成了S型。综上可知,脂溶性树脂内保护层较适宜的厚度为5~10 g/m2,采用夹层包膜工艺能更好的发挥水基树脂的控释性能。

       

      Abstract: To improve the controlled release properties of water medium resin as coating material (WMRM), multi-layer coating technique that based on a bottom spraying fluid-bed coater was used to manufacture double and triple layers coating urea that were made from the WMRM as a coating layer and the additive lipid soluble resin (LSR) as the isolation layer. The double layers consisted of a coating layer as the inner one and an isolation layer as the outer one, the triple layers consisted of two isolation layers and a coating layer between them. Further more, the effects of double and triple layers coating technique on controlled release properties of coating layer with the WMRM were evaluated via the nutrient release characteristics from the multi-layer coating ureas. The results as follows, the nutrient longevity of the coated ureas by the triple layers coating technique could be extended as five times as that by double layers coating technique. By the triple layers coating technique, the thickness of the inner isolation LSR layer from 5 to 15 g/m2 could affect the longevity hardly. With the same technique, the triple layer coating urea had longevity as long as about 260 days with 50 g/m2 WMRM as the coating layer and 10 g/m2 LSR as the outer isolation layer. However, nutrient release patterns of triple layers coating ureas were affected by thickness of the inner isolation layer. When the outer isolation material applied was 10 g/m2 and more, the nutrient release curve was transformed from parabolic to sigmoid. It concluded that the triple layers coating technique which with the WMRM as the coating layer and the LSR as the isolation layer could improve the controlled release properties of the WMRM significantly. The appropriate amount of the inner isolation LSR layer is among 5 and 10 g/m2.

       

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