Chemistry: fertilizers – Processes and products – Forms or conditioning
Patent
1979-06-22
1981-11-10
Lander, Ferris H.
Chemistry: fertilizers
Processes and products
Forms or conditioning
521 63, 47DIG10, 71 27, A01N 2500
Patent
active
042996139
ABSTRACT:
Compositions of and a method for preparing polymeric formulations that gradually, continuously and uniformly release various compounds over a long period of time in ionic form that are well recognized as essential to the growth of agricultural commodities. The compounds, such as inorganic salts of varying water solubilities, are monolithically incorporated in a thermoplastic polymeric matrix usually of two thermoplastic polymers, for example, a copolymer of poly(ethylene-vinyl acetate) or a copolymer of ethylene and propylene. Release is generally conditioned upon the presence of moisture and is proportional to the moisture content of soil treated with the subject invention. Release rate is tailored to a given desirable condition by regulation of the free volume and/or porosity within the polymer matrix and through dispenser geometry. Free volume is maintained at the level conducive to agent release such as through the use of free volume modifying secondary thermoplastic additives such as low density polyethylene; and porosity is controlled through the use of porosity enhancing agents appropriately termed porosigens. Said porosigens can be the low or moderate soluble salts such as the carbonates, bicarbonates, sulfates, phosphates, nitrates, etc.; of the alkali metals, the alkaline earths, or ammonium. Upon exposure to moisture, water ingress into the dispensing pellet removes said porosigen through dissolution processes thus creating a porous network permitting water contact with the incorporated nutrient molecules and their gradual egress in said water over a period of time such as for about a couple months to four years, or longer.
REFERENCES:
patent: 2791496 (1957-05-01), Rice
patent: 2797985 (1957-07-01), Larson
patent: 2891355 (1959-06-01), Nelson
patent: 3059379 (1962-10-01), Attoe
patent: 3372019 (1968-03-01), Fox
patent: 3794478 (1974-02-01), Dirksen
patent: 4019890 (1977-04-01), Fujita et al.
patent: 4111684 (1978-09-01), Thomas et al.
Powell; Controlled Release Fertilizers; 1968; Noyes Development Corp.; pp. 181-182.
Environmental Chemicals, Inc.
Lander Ferris H.
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