Chemistry: fertilizers – Processes and products – Forms or conditioning
Reexamination Certificate
1999-04-23
2001-08-14
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Forms or conditioning
C071S064060, C264S015000, C264S140000, C264S141000, C424S408000, C514S952000
Reexamination Certificate
active
06273929
ABSTRACT:
This invention relates to formulations of agricultural chemicals, minerals and other substances. It is more particularly concerned with the methods of preparing water dispersable granules containing such substances. The present invention provides an improved method of forming granules containing agricultural chemicals.
Agricultural chemicals are formulated in a number of ways, e.g. as large granules (prills) for direct application to soil, pasture or crops, emulsifiable concentrates, liquid flowable concentrates and wettable powders which are normally diluted with water for application. Liquid flowables and wettable powders comprise the majority of the agricultural chemical formulations sold throughout the world. The former are aqueous suspension and while generally giving satisfactory performance, can settle out of suspension during storage requiring vigorous mixing to re-suspend. Because of the high water content (generally around 50%), packaging and freight costs are increased.
Wettable powders are generally produced by first blending the technical grade chemical, with surfactants (wetting and dispersing agents), fillers and possibly other ingredients. The mixture is then passed through an air-mill or other suitable milling device to reduce the size of the additives as well as produce an intimate mixture of the components.
The resultant wettable powder is generally very bulky and becomes air borne readily. This can be hazardous to the user in the case of irritant or toxic materials.
Water dispersible granules (also known as dry flowables) containing agricultural chemicals are designed to disperse readily in water and remain in suspension, i.e. perform as well as liquid flowables and wettable powders when prepared for spray application to soil or plants. One desirable aspect of dry flowable materials is their applicability to solid chemicals of low water solubility. The usual method of producing “dry flowables” is to convert the active agent to a wettable powder formulation by blending and milling the ingredients of the formulation. The resultant powder is then converted to a granule by agglomeration using a pan-granulator or similar device using water or water containing a binder. This is a rather crude process and control of granule size is difficult to achieve.
Water dispersible granules may also be made by mixing the desired ingredients of the granules into an extrudable form, extruding the mix and then drying, if required, the extruded product. Mechanical agitation may or may not be required or preferred to adjust the size of the granules. Extrusion methods practiced in the art may also include mixing water with the composition prior to extrusion.
U.S. Pat. No. 5,443,764 provides a method for forming a water dispersible granule comprising mixing the desired ingredients of the granules in the presence of water to form an extrudable wet mix, extruding the wet mix, and rolling the wet extrusions to break down the extrusions to form granules, and optionally drying the granules.
The present inventor has discovered that especially for active ingredients of extremely low water solubility (i.e., less than about 10 grams per liter water or 1%), the extrusion process may surprisingly be made more efficient, without reduction in biological effect of the active ingredient, if an organosilicone surfactant is added in minor amounts to the active ingredient mixture prior to extrusion.
The present invention also provides an extrusion process and extrudable and extruded compositions which contain crystalline materials (i.e., active and/or inert ingredients) which have a glass transition temperature (T
g
) of less than about 65° C., alternatively, less than about 75° C. By lowering the temperature of operation of the extrusion process, the present invention makes it possible to extrude materials, such as active and/or inert ingredients which have a glass transition temperature (T
g
) of less than about 65° C., alternatively, less than about 75° C., more efficiently, while maintaining the crystalline structure of the active and/or inert material. Previously, extrusion of such active and/or inert materials at higher temperatures created amorphous solids which deteriorated the water dispersability of the extruded product. Accordingly, the present invention provides improved extruded water dispersible products.
The organosilicone of the present invention is preferably solubilized in water used to create the “dough” consistency required for extrusion, as opposed to being added to the premix powder directly.
The ingredients of the extrudable composition of the present invention will generally contain one or more active chemical components which may be liquid or solid at ambient temperature and either of an insoluble or water soluble type.
Typically the active chemical component comprises from 1 to 99%, preferably from 20 to 95% by weight of the dry weight of the composition, more preferably about 50 to 80% by weight of the dry weight of the composition.
The process of the invention may be performed using a wide range of active ingredients.
Examples of active ingredients include agricultural chemicals such as pesticides, herbicides, fungicides, insecticides and fertilisers; pigments; dyestuffs; pharmaceuticals and trace elements.
Examples of herbicidal active ingredients may be selected from one or more of: benzo-2,1,3-thiadiazine-4-one-2,2-dioxides and such as bentazon; hormone herbicides such as MCPA, dichlorprop, MCPB and mecoprop; 3-[4-(4-halophenoxy)phenyl]-1,1-dialkylureas such as chloroxuron; dinitrophenols and their derivatives, for example, DNOC, dinoterb and dinoseb; dinitroaniline herbicides such as dinitramine, nitralin and trifluralin; phenylurea herbicides such diuron and fluometuron; phenylcarbamoylphenylcarbamates such phenmedipham and desmedipham; 2-phenylpyridazin-3-ones such as as pyrazon; uracil herbicides such as lenacil, bromacil and terbacil; triazene herbicides such as atrazine, simazine and aziproptryne; 1-alkoxy-2-alkyl-3-phenylurea herbicides such as linuron, monolinuron and chlorobromuron; pyridine herbicides such as clopyralid and picloram; 1,2,4-triazin-5-one herbicides such as metamitron and metribuzin; benzoic acid herbicides such as 2,3,6-TBA, dicamba and chloramben; anilide herbicides such as balachlor, alachlor, propachlor and propanil; dihalobenzonitrile herbicides such as dichlobenil, bromoxynil and ioxynil; haloalkanoic herbicides such as dalapon and TCA; diphenylether herbicides such as fluorodifen and bifenox; N-(heteroarylaminocarbonyl)benzenesulphonamides such as DPX 4189; Aryloxyphen oxyproprionate herbicides such as fluazifop and diclofop; cyclohexane-1-3-dione derivatives such as alkoxydim-sodium and tralkoxydim; bipryidylium herbicides such as paraquat and diquat; organoarsenical herbicides such as MSMA; amino acid herbicides such as glyphosate; and other herbicides such as dipenamid and naptalam.
Preferred herbicides include diuron, atrazine, simazine, cyanazine, oryzalin, fluometuron, methazole, metoxuron and hexazinone.
Examples of fungicides include imazalil, benomyl, carbendazim (BCM), thiophanate-methyl, captafol, folpet, captan, sulphur, carbamates, dithiocarbamates, phenyl-tin compounds, carbathiins, dicarboximides (including iprodione, vinclozolin, procymidone), copper oxychloride, triforine, dodemorph, tridemorph, dithianon, pyrazophos, binapacryl, quinomethionate, panoctine, furalaxyl, aluminium tris(ethylphosphonate), cymoxanil, ethirimol, dimethirimol, fenarimol, fenpropidin, fenpropimorph, propiconazole, bupirimate, metalaxyl, ofurace, benalaxyl, oxadixyl, chlorothalonil, metaxanine, triazole derivatives such as triadimefon, triadimenol, diclobutrazol, flutriafol and penconazole and ergosterol-synthesis inhibiting fungicides.
Preferred fungicides for use as an active ingredient may include captan, thiram, mancozeb, dichlofluanid, metiram and vinclozolin.
Examples of insecticides which may be used as an active ingredient may include pyrethroids such as cypermethrin organophosphorus insecticides, pirimor croneton, dimethoate,
BASF Corporation
Langel Wayne
Nixon & Vanderhye P.C.
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