US 6,284,278 B1Granted

Controlled release chemicals

AssigneeContrix Ltd.

InventorsDaniel Waldman, Emil Polyansky

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Abstract

Method for the production of encapsulated water-soluble granulated chemicals (fertilizers, salts, pesticides, etc.) with slow controlled release in water and soil with a uniform distribution of the chemicals in a melted thermoplastic, biodegradable and inert polymer composition, with subsequent formation of clots, granules or other shapes. The uniform cross-linked polymer compositions are produced by combining the process of polymerization of neutralized unsaturated carboxylic acids and the process of polycondensation of thiourea with formaldehyde, and the cross-linking of the obtained macromolecules with sulfur. Thus method makes it possible to obtain encapsulated chemicals with a wide range of use, containing up to 85% of the target product, with a gradual release which lasts for up to 180 and more days.

Claims36

Dependent claims

A method for the production of water-soluble granulated chemicals with slow controlled release in water and soil, comprising:

encapsulating said chemicals with 15%-35% of a thermoplastic, biodegradable and inert polymer composition, whereby said encapsulating comprises the steps of:
mixing an inert polymer composition with said chemicals;
crushing the obtained mixture of said chemicals and said polymer composition;
and
moulding the crushed mixture to form clots or granules;
whereby said polymer composition is prepared by
polymerization of neutralized unsaturated carboxylic acids, or of a suitable oil, in the presence of a neutralizing agent, an amine compound and plasticizer, resulting in a polymer comprising the structure of fragment A:
wherein R is CnH2n;
Me is metal;
or a suitable oil thereof;
polycondensation of thiourea and formaldehyde in the presence of an amine compound and plasticizer, resulting in a polymer comprising the structure of fragment B;
and
crosslinking fragments A and B with a sulfur-containing compound.

10 more elements

Dependencies are inferred from the claim text.