Method of microencapsulating an agricultural active having a high melting point and uses for such materials

Abstract

A method of producing a controlled release form of an agricultural active material includes the provision of an organic liquid composition in which the active is present, but where the liquid composition is free from aromatic solvents and is maintained below the normal melting point of the active. The liquid composition is formed into small droplets and the droplets are enclosed by a non-water soluble shell to provide microcapsules, the shell of which is designed to release the agricultural active at a pre-selected controlled rate when the microcapsule is exposed to natural environmental conditions. Controlled release forms of agricultural actives are also provided.

Description

BACKGROUND OF THE INVENTION [0001] (1) Field of the Invention [0002] The present invention relates to methods for the microencapsulation of an agricultural active having a high melting point, and more particularly to methods for the microencapsulation of such material while maintaining the temperature of the agricultural active below its normal melting point and without contacting the active with an aromatic solvent. [0003] (2) Description of the Related Art [0004] Materials that affect the growth and development of agronomically important plants, or that provide some type of protection of plants from pests and diseases, are commonly referred to as agricultural actives. Such materials are widely used in modern agriculture and provide benefits of increased yield, vigor and overall plant health. However, some agricultural actives have harmful effects if they are ingested or otherwise contacted by humans or other animals. [0005] The most common method for using agricultural actives is ...

AI Technical Summary

Benefits of technology

"The present invention is about a new method for producing a controlled release form of an agricultural active ingredient that has a normal melting point. The method involves creating small droplets of the active ingredient and enclosing them in a non-water soluble shell. The shell can be designed to release the active ingredient at a pre-determined rate when exposed to natural environmental conditions. The invention also includes a new method for reducing the melting point of the active ingredient. The new methods can be used to create new controlled release forms of agricultural active ingredients that have improved solubility and can be used in agricultural applications."

Problems solved by technology

However, some agricultural actives have harmful effects if they are ingested or otherwise contacted by humans or other animals.

But wind, runoff and groundwater leaching can cause undesirable movement of the active, which can result in its unintended contact with plants and animals in streams, neighboring fields and homes.

Furthermore, such movement of the active from the zone where protection is desired can result in reduction of the concentration of the active to below efficacious levels by the time the target pest arrives.

Irreversible binding of the active to components of soil exacerbates this problem.

For example, microcapsules formed around liquid droplets have regular spherical geometry, coatings of even thickness, and lack sharp edges and concave surfaces, which can occur in coatings of solid particles, and which could cause uneven coating thickness or even lack of a coating on some parts of the active.

The microcapsules were designed to maintain the encapsulated material until the capsule was ruptured, and would not have been suitable for the controlled release of the encapsulated materials through the walls of the capsule.

Despite the advantages provided by microcapsules having polyurea shells that enclose liquid cores containing agricultural actives, the methods that are known for the formation of these structures have certain limitations that limit their use with certain highly promising actives.

For example, if the agricultural active has a melting point that is close to, or higher than, the preferred range of polymerization temperature for polyurea shell formation, it is difficult to liquify the active in order to form the microcapsule.

Since many aromatic solvents are phytotoxic, their use in controlled release formulations intended for application to plants or seeds would appear to be potentially harmful to the plant.

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