Granular controlled release agrochemical compositions and process for the preparation thereof

Abstract

A granular agrochemical composition is disclosed including a granular core material having a water soluble portion with a first coating layer applied on the surface of the core material and a second coating layer applied on the surface of the first coating layer. The first coating layer includes a wax composition having a biologically active ingredient incorporated therein and the second coating layer includes a polymeric composition. The granular agrochemical composition exhibits a controlled rate of release of the biologically active ingredient therefrom over a period greater than about 30 days from the date of initial exposure of the granular composition to moisture whereby essentially all of the biologically active ingredient incorporated in the wax material of the first coating layer is released from the granular composition before the water soluble portion of the granular core material is released from the granular composition.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to granular agrochemical compositions and to processes for producing such compositions. More particularly, it relates to controlled release agrochemical compositions having a first coating layer comprising a wax composition with a biologically active ingredient incorporated therein applied on the surface of a core material and having a second coating layer comprising a polymeric composition applied on the surface of the first coating layer and to processes for preparing such compositions. [0003] 2. Description of Related Art [0004] Agrochemicals as referred to herein include biologically active ingredients / plant protection products such as insecticides, herbicides, fertilizers, growth regulators, pheromones, biostimulants, acaricides, miticides, nematocides, fungicides and the like. Such agrochemicals are well known and are in common usage for controlling pests and diseases and for prom...

AI Technical Summary

Benefits of technology

[0025] The present invention involves the development of a new system for release of active ingredients, such as herbicides, growth regulators, pheromones, bactericides, insecticides, acaricides and fungicides and the like, over a defined period of time with high efficiency.

Problems solved by technology

Too much active ingredient, however, is inefficient and not desired because of environmental and economic concerns.

Furthermore, higher amounts of active ingredient lead to increased risks of leaching to ground water or surface water.

Higher amounts can also lead to phytotoxicity for the crop.

Insufficient levels of active ingredients results in lack of control of the pest and increase the risk of resistance.

However, multiple applications of active ingredients becomes labor and cost intensive.

With conventional applications of liquid or powder formulations, relatively high amounts of active ingredients are applied several times to assure control of pests over a longer period of time, typically 3-6 times for seasonal control, and users are exposed to the active ingredients during each application, which is undesirable.

When active ingredients are applied in granular form instead of by spraying or dusting, the risk of exposure to the active ingredient is more limited.

Thus high concentrations result in relatively more degradation and leaching.

In general, known controlled release granular active ingredients suffer serious limitations.

They generally do not deliver the active ingredient to the biological system for periods of greater than about 30 days from the date of initial exposure to moisture and / or they do not completely release the active ingredient.

The practical limitations of systems that release the active ingredient in less than about 30 days are that they must be periodically reapplied during the growing season resulting in additional cost.

The limitations of systems which do not completely release the active ingredient in the desired period of time are related to efficiency.

This incurs additional cost to the user.

Furthermore, the residual, unreleased active ingredient poses an environmental threat and can lead to biological resistance in the pest.

Active ingredient that is not released cannot be used for controlling a pest or disease and will give undesirable residues of active ingredient.

In the long run this can lead to build up of chemicals in soil and this is even less desirable.

However, the products disclosed in EP Patent 079668 are structurally distinct from the products of the present invention and, accordingly, disadvantageously fail to exhibit a controlled rate of release of the pesticide over a period greater than about 30 days from the date of initial exposure of the product to moisture in a manner such that essentially all of the pesticide coated on the core is released from the granular composition before the water soluble portion of the core material is released from the product as is achieved with the compositions of the present invention.

Thus, the products disclosed in these patents fail to exhibit a controlled rate of release of the pesticide over a period greater than about 30 days from the date of initial exposure of the product to moisture in a manner such that essentially all of the pesticide coated on the core is released from the granular composition before the core material is released from the product.

The slow release from this matrix is limited to oil-soluble pesticides.

Thus, the release rate of such granules decreases over time resulting in initial fast release of active ingredients which provides high amounts of active ingredient in the soil at the start, and a slow release at the end.

A disadvantage of these biodegradable products is that the release of active ingredient depends on the speed of degradation of the polymer and this degradation depends on the activity of ambient microorganisms.

Thus, the release rate of active ingredients varies and it is difficult to match the release precisely with the minimal required active ingredient concentrations.

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