AGENT FOR IMPARTING SUSTAINED-RELEASE PROPERTIES TO AGRICULTURAL CHEMICALS, SUSTAINED-RELEASE AGRICULTURAL CHEMICALS, AND PROCESS FOR THEIR PREPARATION

摘要

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.