Composite particles comprising core particles of an agricultural chemical as an agriculturally active ingredient surrounded by an outer layer of fine hydrophobic particles are produced by depositing, on the surface of particles of a solid particulate agriculturally active ingredient, i.e., a compound with agricultural activity, fine particles of a hydrophobic substance having an average particle size of at most 1/5 of that of said agriculturally active ingredient in a predetermined weight ratio of the active ingredient to the hydrophobic substance, or anchoring the hydrophobic substance into the surface of the particles of the active ingredient to thereby fix the hydrophobic substance. In addition, the individual particles of the hydrophobic substance deposited or fixed on the surface of the agriculturally active ingredient as described above may be bound to each other by impact force and/or frictional heat to form a continuous covering film, thus giving composite particles of the agriculturally active ingredient comprising core particles of the active ingredient surrounded by the covering film of the hydrophobic substance. These composite particles can gradually release the active ingredient constituting the core particles through the surrounding layer of the hydrophobic substance at a controlled rate into water, thus showing sustained-release properties of the agriculturally active ingredient. Therefore, the composite particles are useful as an agricultural chemical having advantageous sustained-release properties and showing persistent biological effects. The composite particles can be made into an agricultural composition adapted for various preparations by mixing with various conventional adjuvants.
通过在固体颗粒状农业活性成分(即具有农业活性的化合物)的颗粒表面沉积疏
水性物质的细小颗粒(其平均粒径不超过所述农业活性成分的 1/5),制得由作为农业活性成分的农业
化学品核心颗粒和外层疏
水性细小颗粒组成的复合颗粒、疏
水性物质的细颗粒,其平均粒径至多为所述农业活性成分的 1/5,活性成分与疏
水性物质的重量比预先确定;或将疏
水性物质锚定在活性成分颗粒的表面,从而固定疏
水性物质。此外,上述沉积或固定在农用活性成分表面的各个疏
水性物质颗粒可以通过冲击力和/或摩擦热相互结合,形成连续的覆盖膜,从而得到由疏
水性物质覆盖膜包围的活性成分核心颗粒组成的农用活性成分复合颗粒。这些复合颗粒可以通过周围的疏
水性物质层以可控的速度将构成核心颗粒的活性成分逐渐释放到
水中,从而显示出农业活性成分的持续释放特性。因此,这种复合微粒可作为一种农用
化学品,具有良好的持续释放特性,并显示出持久的
生物效应。通过与各种常规佐剂混合,复合颗粒可制成适用于各种制剂的农用组合物。