Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Patent
1996-03-20
1998-02-03
Levy, Neil S.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
424405, 424408, 424419, 504116, 71DIG1, A01N 2512
Patent
active
057141576
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention pertains to rapidly disintegrating water-dispersible granular compositions comprising active ingredients of value in agriculture.
Water-dispersible granular compositions are becoming increasingly popular in agriculture. Accordingly, it is advantageous to discover improved compositions and methods of production. Most granulation methods in current use, generally referred to herein as wet granulation, require introduction of water for granulation and then a drying step to remove the water. The drying step is expensive, time-consuming and may create dust, and it would be advantageous if granulation could be accomplished without water.
The granular agricultural compositions are most commonly applied by diluting an effective dose with water in a mix tank and spraying the locus to be treated. An important feature of the granules is the rate at which they will disintegrate in the spray water to form the final dispersion or solution. Faster disintegration rates are preferred.
World Patent WO 92/15197 discloses water-dispersible granular compositions of agricultural active ingredients which were made by heat extrusion. Granulation is accomplished by the fusion of heat-sensitive components; no water is added and no drying step is required. A limitation of the granular compositions of this art though is that they require incorporation of effervescence in order to disintegrate in water as rapidly as granular compositions made by wet granulation. The problem with effervescent ingredients is that they are very sensitive to moisture and tend to react prematurely during manufacture and storage. Extra precautions in handling must be taken, and shelf-life may be limited.
The present invention is an improvement in the prior art by the selection of ingredients which yield noneffervescent granular compositions made by heat extrusion having superior disintegration rate and improved shelf-life.
SUMMARY OF THE INVENTION
The invention is a rapidly disintegrating water dispersible granular composition for agricultural applications. The composition comprises by weight based on the total weight of the composition:
(a) 0.01-80% of one or more agriculturally active ingredient
(b) 0-60% of a base
(c) 5-95% of urea
(d) 1-30% of one or more urea modifier, and
(e) optionally one or more additives selected from the group consisting of wetting agents, dispersants, lubricants, anti-caking agents, chemical stabilizers and inert diluents, the sum of all ingredients totaling 100%.
Preferably the active ingredient is 0.03-70%, the urea is 7-75% and the urea modifier is 3-15%.
More preferably the active ingredient is 10-65% and the urea is 10-65%.
Another embodiment of the invention is a process for preparing a rapidly disintegrating water dispersable granular agricultural composition comprising
(a) extruding a dry premix through a die or a screen at elevated temperatures, preferably below 115.degree. C., said premix comprising the composition described above, and
(b) cutting, breaking, or sieving the extruded strands to form granules.
The active ingredient is at least one pesticide or a chemical used for crop protection. Especially advantageous compositions comprise a mixture of two active ingredients. More specifically, ingredients are selected from the class of herbicides, fungicides, bactericides, insecticides, insect antifeedants, acaricides, miticides, nematocides, and plant growth regulants.
The addition of base is preferred when the composition comprises an acidic active ingredient that becomes water soluble as a salt. Examples of acidic actives of this sort are glyphosate, 2,4-D and the sulfonylurea class of herbicides. Levels of base include up to a 2:1 mole ratio of a base to salt-forming active ingredient, preferably a mole ratio range from 0.4:1 to 1.6:1, and most preferred a mole ratio range from 0.8:1 to 1.2:1. In any case, the mount of base will generally not exceed 60% of the composition. Suitable bases include but are not limited to alkali metal and alkaline earth metal oxides
REFERENCES:
patent: 5100667 (1992-03-01), Chan et al.
Sandell Lionel Samuel
Wysong Robert David
E. I. Du Pont de Nemours and Company
Levy Neil S.
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