WO1996027288A1

WO1996027288A1 - Encapsulated bicarbonate-containing agrochemical compositions

Info

Publication number: WO1996027288A1
Application number: PCT/US1996/001529
Authority: WO
Inventors: M. Stephen Lajoie; Amy Joseph; Keith A. Jones; Anthony E. Winston
Original assignee: Church & Dwight Company, Inc.
Priority date: 1995-03-08
Filing date: 1996-02-13
Publication date: 1996-09-12
Also published as: AU4775896A

Abstract

This invention provides a dry powder composition which is in the form of encapsulated particles. The particles are comprised of (1) a particulated inorganic salt ingredient such as sodium, potassium or ammonium bicarbonate or mixtures thereof; and (2) a blend of an agrochemical ingredient and a hydrophilic polymer which is adhered as a continuous film coating on the surface of the inorganic salt particles. The agrochemical ingredient can be a mixture of two or more biologically active compounds. The particle film coating functions as a slow-release medium in the presence of moisture.

Description

ENCAPSULATED BICARBONATE-CONTAINING AGROCHEMICAL COMPOSITIONS

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application is a continuation- in-part of patent application S.N. 08/294,809, filed September 22, 1994; which is a continuation of patent application S.N. 08/077,384, filed June 17, 1993, now abandoned; which is a divisional of patent application S.N. 07/881,697, filed May 12, 1992, now abandoned; incorporated by reference.

BACKGROUND OF THE INVENTION Fine chemical sales for agricultural purposes in the United States totalled about 13 billion dollars in 1990. The United States market for organic pesticide intermediates is about 986 million dollars per year, which include chemicals such as nitrites, amines, carboxylic acids, anilines, organophosphorus compounds, mercaptans, phenols, benzenes, alkane/alkenes, pyridines, alcohols and aldehydes.

Agricultural pesticide sales at the producer level in the United States in 1990 were about 5.5 billion dollars. Pesticide sales represent an important segment of the agrochemical industry in the United States and in other world markets, mainly for fungicide, herbicide and insecticide applications.

The control of phytopathogenic fungi is of great economic importance since fungal growth on plants or on parts of plants inhibits production of foliage, fruit or seed, and the overall quality of a cultivated crop.

There is also a serious worldwide problem of mold growth in food materials, such as grains, animal feeds, animal feed ingredients, and hay. This problem is most serious in tropical zones of both the eastern and western hemispheres, where sustained high humidities cause excessive moisture to be absorbed in such products.

Because of the vast economic ramifications of fungal propagation in agricultural and horticultural cultivations, a broad spectrum of fungicidal and fungistatic products have been developed for general and specific applications. With respect to herbicide developments, weed control is essential in the cultivation of important agricultural crops such as corn, peanuts and cotton, and in the cultivation of many horticultural species. Also, the presence of weeds on non-cropped areas can be a fire hazard, or can result in undesirable drifting of sand or snow, or can cause discomfort to persons with allergies. Control of weeds is particularly beneficial when it permits the selective control of such plants without concurrent injury to desirable crops or vegetation. Chemical herbicides are classified according to the type of activity they possess. A given compound may have more than one type of activity depending upon its mode of application and the rate at which it is applied. In addition, herbicides are usually classified as selective or non-selective pre-emergents or post-emergents.

The most effective pre-eraergence herbicide is one which is selective in its nature. If the designated compound can kill the seed and germinated seedlings of undesirable plants without harm to the seed and germinated seedlings of the crop, there will not be any problem of overpenetration of the soil by the herbicide.

Post-emergence herbicides are applied after the crop and weeds have attained substantial height. In general, if a compound is found to have post-emergence activity it will not be selective.

Some herbicides are effective through contact, and others are taken up from the soil by root systems. Herbicide types include defoliants, desiccants, eradicants, systemics and selective herbicides, and related plant growth regulants. With respect to insecticide developments, a wide variety of ornamental and agricultural plants are susceptible to infestation by insects and arachnids. The pests inflict damage by consuming foliage and roots, withdrawing juices from the plants, secreting toxins, and infecting with diseases.

Field crops which require protection from pests include such valuable crops as soybeans, corn, peanuts, cotton, alfalfa and tobacco. In addition, vegetables such as tomatoes, potatoes, sugar-beets, carrots, and the like, and nuts, ornamentals, apples, peaches, peas, citrus fruit and grape also require protection from the ravages of such pests. Insects which are difficult to control include those which inhabit the soil and cause destruction of the root systems of valuable agricultural crops. Corn rootworms are the larvae of several beetle species of the genus Diabrotica. The adult beetles lay their eggs in the soil of a maturing corn crop. The eggs lay dormant in the soil until the following spring, then they hatch in response to favorable soil temperatures and the larvae feed on the roots of young corn plants causing reduction in yield.

A broad scope of insecticide compounds have been developed to combat insects which are harmful to agricultural and horticultural plants. Illustrative of insecticide compositions are those described in United States Patent Numbers 3,217,037; 3,506,698; 3,576,834; 3,636,111; 3,755,364; 3,875,232; 4,028,413; 4,128,581; 4,415,743; 4,640,927; 4,804,653; 4,839,349; 5,010,068;

5,087,456; 5,087,456; 5,096,928; and references cited therein.

Of particular interest with respect to the present invention embodiments are pesticide compositions which contain one or more inorganic bicarbonate or carbonate compounds. It is known that bicarbonate and carbonate compounds exhibit biocidal properties for agricultural purposes. Phytopathology, L, 169 (1931) by R. H. Marloth describes studies involving the physiology of fungi. The reference reports studies which demonstrate that sodium and potassium bicarbonate and carbonate salts are toxic to fungi such as Penicillum italicum and Penicilium diαitalum.

Japanese patent 56043207 describes a biocidal composition containing sodium bicarbonate and a polyglycerol fatty acid ester. The biocide controls Penicillum diαitatum on oranges, Sphaerotheca fuliσenea on cucumbers, Piricularia oryzae on rice, and mosaic virus on tomatoes. Japanese patent 57062208 describes horticultural fungicides in which the addition of sodium bicarbonate to polyoxin or thiophanatemethyl increases the fungicidal activity of the organic biocide against botrytis cinerea on cucumbers.

There remains a continuing need for the development of new and more effective agrochemical compositions which possess preventive, curative and systemic biological activity for the protection of cultivated plants, with a minimum of phytotoxic side effects.

Accordingly, it is an object of this invention to provide an agricultural composition which is a combination of inorganic and organic compounds exhibiting agrochemical properties.

It is another object of this invention to provide a dry particulate composition which is a combination of ingredients which includes a bicarbonate-containing inorganic ingredient which enhances the biocidal activity of a pesticide ingredient in agricultural applications.

It is a further object of this invention to provide a slow-release powder composition which has a content of encapsulated particulate bicarbonate salt and one or more other agrochemical ingredients.

Other objects and advantages of the present invention shall become apparent from the accompanying description and examples. DESCRIPTION OF THE INVENTION One or more objects of the present invention are accomplished by the provision of a slow-release powder composition composed of encapsulated particles which are a combination of ingredients comprising (1) a particulate inorganic salt ingredient selected from the group consisting of alkali metal and ammonium bicarbonates; and (2) a blend ingredient comprising (a) an agrochemical compound, and (b) a water-soluble or water-dispersible hydrophilic organic polymer; wherein the blend ingredient is in the form of a continuous film coating on the surface of the inorganic salt particles, and the blend ingredient coating functions as a slow-release medium in the presence of moisture.

In another embodiment this invention provides an agrochemical formulation which is a dry blend of at least two slow-release powder compositions of the type defined hereinabove.

In a further embodiment this invention provides an aqueous agrochemical formulation which contains a dispersed phase of a slow-release powder composition of the type defined hereinabove, and as illustrated in the Examples.

The inorganic salt ingredient crystallites can have an average particle size in the range between about 1-18 microns in a powder composition which is adapted for utility as a pesticide dusting powder. For other applications the particulate inorganic salt ingredient crystallites can have an average particles size between about 200-800 microns, before being encapsulated with a continuous film coating of the blend ingredient on the surface of the particles.

The coating on the inorganic salt particles can be a single layer or multiple layers, and typically will comprise between about

5-70 weight percent of the dry particle weight. The coating thickness typically will vary in the range between about 0.1-30 microns.

The content of the agrochemical compound or mixture of agrochemical compounds in the blend ingredient coating on the inorganic salt particles can very between about 0.5-35 weight percent, based on the coating weight.

The term "average particle size" as employed herein refers to the average of the largest dimension of particles.

The term "water-soluble" as employed herein refers to a hydrophilic polymer which has a water-solubility of at least about one gram per 100 grams of water at 25°C. The term "water-dispersible" as employed herein refers to a hydrophilic polymer which has a water-solubility of less than about one gram per 100 grams of water at 25^βC, and which forms a stable phase when dispersed in an aqueous medium.

The inorganic salt ingredient is selected from compounds which include sodium bicarbonate, potassium bicarbonate and ammonium bicarbonate. In a further embodiment, the inorganic salt ingredient can include between about 0.5-20 weight percent of an additional compound selected from sodium carbonate, potassium carbonate, lithium carbonate and ammonium carbonate, based on the weight of inorganic salt ingredient. Illustrative of inorganic salt ingredients in a formulation are sodium, potassium, lithium or ammonium bicarbonate; or mixtures such as sodium bicarbonate and potassium bicarbonate; sodium bicarbonate and ammonium bicarbonate; potassium bicarbonate and ammonium bicarbonate; sodium bicarbonate, potassium bicarbonate and ammonium bicarbonate; sodium bicarbonate and potassium carbonate; potassium bicarbonate and sodium carbonate; and the like. Multiple inorganic salt compounds can be utilized in a broad range of molar quantities relative to each other. The molar quantity of a carbonate salt compound normally is determined by pH control considerations when aqueous formulations are prepared. The content of a carbonate salt compound can be varied to control the pH at a desired level in the range of 7.5-12. Aqueous pesticidal formulations of the present invention tend to have a higher biocidal activity at higher pH values. The agrochemical constituent of the particle coating can consist of one or more biologically active organic compounds. Biologically active organic compounds are illustrated by fungicides, herbicides, insecticides, plant growth regulators, fertilizers, and the like.

An agrochemical fungicide ingredient can be selected from a wide variety of organic compounds or mixtures which are known and used in agriculture and horticulture applications, such as those listed in Agricultural Chemicals, Book IV, Fungicides, 1989 Revision (W. T. Thomson, Thomson Publications, Fresno, California 93791) . The general categories of fungicidal- active compounds include anilides, dithiocarbamates, halogenated derivatives, heterocyclic nitrogen derivatives, organometallic derivatives, and the like. Illustrative of fungicidal compounds are carbendazim, benomyl, thiophanate-methyl, thiabendazole, fuberidazole, dichlofluanid, cymoxanil, oxadixyl, metalaxyl, furalaxyl, benalaxyl, fenarimol, iprodione, procymidone, vinclozolin, penconazole, myclobutanil, pyrazophos, ethirimol, ditalimfos, tridermorph, triforine, nuarimol, triazbutyl, guazatine, propiconazole, prochloraz, flutriafol, chlortriafol, triadimefon, triadimenol, dichlobutrazol, fenpropi orph, fenpropidin, chlorozolinate, fenfuram, carboxin, oxycarboxin, methfuroxam, dodemorph, blasticidin S, kasugamycin, edifenphoε, kitazin P, cycloheximide, phthalide, probenazole, isoprothiolane, tricyclazole, pyroquilan, chlorbenzthiazone, neoasozin, polyoxin D, validamycin A, repronil, flutolanil, pencycuron, diclomezine, phenazin oxide, nickel dimethyldithiocarbamate, techlofthalam, bupirimate, etaconazole, cypofuram, biloxazol,dimethirimol, fenapanil, pyroxyfur, polyram, maneb, mancozeb, captafol, chlorothalonil, anilazine, thiram, captan, folpet, zineb, propineb, binapactryl, nitrothalisopropyl, dodine, dithianon, fentin hydroxide, fentin acetate, tecnazene, quintozene, dichloran, propiconazole, pentachloronitrobenzene, and the like.

An agrochemical herbicide ingredient can be selected from a wide variety of inorganic and organic chemical structures known and used in pest control applications. Amide herbicides are exemplified by commercial products such as Lasso and Dual, which are effective for pre-emergent or pre-planting applications. Arsenical herbicides include cacodylic acid and the salts of monomethylarsinic acid and dimethylarsinic acid. Cacodylic acid is a defoliating or desiccating contact herbicide.

Arsinic acid salts have lower contact toxicity and act through absorption. For purposes of the present invention, the salt form is preferred rather than the free acid form.

Carbamate and thiocarbamate herbicides include Belanal, Betanex, Sutan, Eptam, and similar trademark products. These herbicides usually are applied to the soil and are taken up through the root systems.

Carboxylic acid herbicides are illustrated by commercial products such as Banvel, Ga Ion and 2,4-D. Various of these herbicides can be applied to the soil or to foliage, and are effective against broad leaf weeds.

Dinitroaniline herbicides include Balan and Treflan commercial products, which are applied to the soil to inhibit root growth and shoot growth, and exhibit low translocation.

13

Heterocyclic nitrogen-containing herbicides are illustrated by Aatrex, Basagran, Sencor and Velpar, which are applied to the soil for pre-emergent control. Organophosphate compounds are useful as plant growth regulators and herbicides. This type of organic biocide structure is illustrated by Bensulide and Betasan.

Urea herbicides are nonselective and usually are soil applied. Urea-type commercial products include Lorox and Tupersan.

Quaternary herbicides include commercial products such as Avenge, Diquat and Paraquat, which have utility as contact foliars. Other commercially available herbicides include Atrazine, Bentazon, Bromacil, Casoron, Chloroamben, Delapon, Diuron, Fluometuron, Glphosate, Linuron, Picloram, Trifluralin, and the like. The types of weeds which are controlled by herbicide agrochemicals include barnyard grass, green foxtail, wild oats, nightshade, velvetleaf, annual morningglory, yellow nutsedge, pigweed, downy brome, and the like.

An agrochemical insecticide ingredient can be selected from a wide variety of organic chemical structures, such as those listed in Agricultural Chemicals, Book I, Insecticides, 1989 Revision (W. T. Thomson, Thomson Publications, Fresno, California 93791) .

The general categories of insecticidal- active organic compounds include chlorinated hydrocarbon derivatives, phosphorated derivatives, pyrethroids, acylureas, and the like.

The chlorinated hydrocarbon insecticides usually act as stomach and contact poisons affecting the nervous system. They are persistent in the environment and tend to accumulate in animal fatty tissue, as exemplified by DDT and chlordane.

The organic phosphates generally are contact and/or stomach poisons. They are less persistent in the environment than the chlorinated hydrocarbons. They are toxic since they generally are cholinesterase inhibitors, which interfere with nerve impulse transmission. Most of these compounds are characterized by relatively low LD₅₀ values, although the value for malathion is 1400. Parathion is one of the best known organic phosphate systemic insecticides, and is considered a dangerous material to handle. The carbamates are similar in action to the organic phosphate insecticides. These insecticides usually are not magnified in the food chain, and are characterized by rapid breakdown. The synthetic pyrethroids react well with synergists and exhibit relatively low mammalian toxicity. Generally they break down rapidly and leave little residue.

Illustrative of other insecticidal compounds are chlorfluazuron, chlorpyrifos, chlorpyrifos methyl, bromophos, diazinon, malathion, trichlorfon, dimethoate, phorate, lindane, toxaphene, diflubenuron, methomyl, propoxur, carbaryl, cyhexatin, cypermethrin, permethrin, fenvalerate, dicofol, tetradifon, propargite, and the like.

An agrochemical plant growth regulator ingredient can be selected from the types of organic chemical structures which are known to exhibit phytohormone activity, such as 3-indolealkanoic acids, deterpenoid acids, cytokinins, chloro- substituted phenoxyacetic acids, naphthaleneacetic acids, and the like.

An invention plant growth regulating composition preferably has a content of an organic plant growth stimulant ingredient such as a surfactant. Plant growth regulator compounds include abscisic acid, gibberellic acid, 3-indoleacetic acid, 2,4-dichlorophenoxyacetic acid, 2-naphthylacetic acid, 2,3,5-triiodobenzoic acid, phenyl indole-3-thiolobutyrate, kinetin, zeatin, 6-benzylaminopurine, and the like.

An agrochemical fertilizer ingredient can be selected from nitrogen-containing and phosphorus- containing organic compounds such as urea, melamine, hexamine, benzoquanamine, dicyanodiamide, ammeline, cyanuric acid, melamine nitrate, triethyl phosphite, and the like.

An inorganic agrochemical compound normally is insoluble in the hydrophilic polymer of the coating blend ingredient. It will be present in the particle coating film as a dispersed crystalline particle phase.

An organic agrochemical compound normally is soluble in the hydrophilic polymer of the coating blend ingredient. It will be present in the particle coating film as a dissolved solute in a solid solution.

The application of the blend ingredient coating to the inorganic salt crystallite surfaces is accomplished by conventional means such as pan coating, spray-drying, fluidized coating, centrifugal fluidized coating, and the like. The blend ingredient usually is dissolved in a suitable solvent such as water, methanol, ethanol, acetone, tetahydrofuran, ethyl acetate, dimethylformamide, and the like, as appropriate for a selected polymer species. A coating also can be applied to inorganic salt crystallites in the form of an emulsion or suspension. After the coating medium is applied to the crystallites, the solvent medium is removed by evaporation, thereby forming a continuous film coating which encapsulates the discrete fine grain crystallites.

In a preferred coating procedure, bicarbonate powder is dispersed in a solvent medium which contains coating polymer and agrochemical ingredients. The dispersion is atomized and sprayed into heated air to remove the solvent phase, and to provide a free-flowing polymer-encapsulated bicarbonate powder product.

A hydrophilic polymer employed for coating the inorganic salt crystallites is selected from water-soluble and water-dispersible organic polymers. A mixture of polymers can be employed, and a content of between about 0.5-40 weight percent of a water-insoluble polymer, based on the coating weight, can be included with a hydrophilic polymer. Suitable hydrophilic polymers for coating inorganic salt crystallites include gum arabic, gum karaya, gum tragacanth, guar gum, locust bean gum. xanthan gum, carrageenan, alginate salt, casein, dextran, pectin, agar, 2-hydroxyethyl starch, 2-aminoethyl starch, maltodextrin, amylodextrin, 2-hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose salt, cellulose sulfate salt, polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, polyethylene oxide, polyvinyl alcohol/acetate, polyacrylamide, and the like. Polyvinyl acetate is illustrative of a water- insoluble polymer which can be included as an additional coating component to moderate the hydrophilicity of a hydrophilic polymer coating. Suitable water-insoluble polymers, in combination with a hydrophilic polymer, for coating inorganic salt crystallites include polyvinyl acetate, polyacrylamide, polyvinyl chloride, polystyrene, polyethylene, polyurethane, and the like.

The rate of release of bicarbonate salt core matrix content of the encapsulated particles under moisture conditions can be controlled by the quantity and type of polymer coating on the particle surfaces.

Low molecular weight hydrophilic polymers will release the particle core matrix content at a relatively fast rate in the presence of moisture. High molecular weight polymers which are less 19 hydrophilic will release at a relatively slow rate. Additional rate control is obtained by employing mixtures of polymer components of varied hydrophilicity. Polyethylene glycol (M.W. of 4000) or polyvinyl alcohol will release the particle core matrix content at a relatively fast rate. Polyethylene oxide (M.W. of 4,000,000) or partially hydrolyzed polyvinyl acetate will release at a relatively slow rate. Polyvinylpyrrolidone will release the particle core matrix content at an intermediate rate when in contact with moisture.

In another embodiment this invention provides a dry pulverulent formulation which is a blend of constituents comprising (A) a slow-release powder composition composed of encapsulated particles which are a combination of ingredients comprising (1) a particulate inorganic salt ingredient selected from the group consisting of alkali metal and ammonium bicarbonates; and (2) a blend ingredient comprising (a) an agrochemical compound, and (b) a water-soluble or water-dispersible hydrophilic organic polymer, wherein the blend ingredient is in the form of a continuous film coating on the surface of the inorganic salt particles, and the blend ingredient coating functions as a slow-release medium in the presence of moisture; and (B) a surfactant constituent. The surfactant constituent is a cationic, anionic or nonionic organic compound or a mixture thereof, and the content of the surfactant is in the range between about 0.2-10 weight percent, based on the formulation weight.

Suitable surfactants include cetyltrimethylammonium bromide; sodium lauryl sulfate; sodium dodecylbenzenesulfonate; ammonium lignosulfonate; condensation products of ethylene oxide with fatty alcohols, amines or alkylphenols; partial esters of fatty acids and hexitol anhydrides; and the like.

Optionally, an anti-caking or free-flow aid can be included as an additive in an invention powder composition. Useful additives include mannitol, sorbitol, phosphorus pentoxide, calcium sulfate, barium oxide, calcium chloride, and the like.

As described hereinabove, an invention encapsulated powder composition can be in the form of dusting powders, granules or pellets, and can be utilized as such for pest control or plant growth regulation or fertilization applications.

An invention encapsulated powder composition also can function as a dispersible powder when it contains a surfactant ingredient which facilitates dispersion of the powder in an aqueous medium. 21

A present invention encapsulated powder composition has a unique combination of properties, and provides versatility and advantage in a broad range of agricultural and horticultural applications.

Each of the bicarbonate and carbonate components either singly or together in the inorganic salt ingredient exhibits fungicidal activity when an invention composition is applied in solid form or as an aqueous medium in agricultural pest control applications.

The physical combination of the particulate inorganic salt ingredient and the agrochemical ingredient in the particle surface coating prevents any settling or inhomogeneous separation of the ingredients in a dry powder composition.

The protected polymer-encompassed state of the agrochemical ingredient in the coating contributes stability to the ingredient under variable conditions of temperature and atmosphere during storage.

The molecular interface of inorganic salt ingredient and agrochemical ingredient under field application conditions permits an optimized enhancement of agrochemical efficacy. Less agrochemical ingredient can be utilized to achieve a prescribed degree of pest control or plant growth regulation. The relative quantities of inorganic salt and agrochemical ingredients can be controlled with precision. Administration of parts per million of one or more agrochemicals can be accomplished with ease and efficiency, and phytotoxic side effects can be minimized.

As a further advantage, two or more invention powder compositions can be blended to provide formulations with precise quantities of two or more agrochemicals for polyfunctional activities in agricultural applications.

The following examples are further illustrative of the present invention. The components and specific ingredients are presented as being typical, and various modifications can be derived in view of the foregoing disclosure within the scope of the invention.

EXAMPLE I This Example illustrates a process for the preparation of a slow-release agrochemical powder composition in accordance with the present invention.

Benomyl (8 g) and maltodextrin (30 g) are dissolved in 250 ml of ethanol. KHC0₃ (325 mesh, 125 g) is suspended in the ethanol solution with stirring. The ethanol solvent is removed by evaporation under vacuum. A dry free-flowing KHC0₃ powder is obtained, in which the particles are encapsulated with a continuous film coating of Benomyl/maltodextrin on the surface of the particles.

Both the KHCO_j and Benomyl exhibit slow- release fungicidal activity in agricultural pest control applications, when utilized in solid form, or as a suspension in an aqueous medium. The fungicidal efficacy of the Benomyl is enhanced by the presence of the KHC0₃ ingredient. A more pronounced synergistic effect on the Benomyl fungicide activity is obtained if an equivalent weight of a 50/50 NaHC0₃/KHC0₃ mixture is employed in place of the KHC0₃ content. EXAMPLE II This Example illustrates a fluidized bed procedure for coating particulate bicarbonate powder with an agrochemical-containing hydrophilic polymer in accordance with the present invention.

A fluidized bed vessel is utilized which is equipped with a Wurster air-suspension coater system (WARF) as described in U.S. 4,568,559 and U.S. 4,877,621. A coating solution is prepared by dissolving polyethylene glycol (50 g, Poly-G 2000, Olin Corp.), propylene glycol butyl ether (5 g, PPG 14, Americol) , and urea (15 g) in ethanol (500 g)/water (75 g) . Sodium bicarbonate powder is utilized as the core matrix type of crystallites. The sodium bicarbonate (Particle Size Technology, Inc.) has an average particle size of about 5 microns, and 90 percent of the particles have a diameter less than 20 microns. The powder is charged into the coating chamber of the coated system.

Compressed air is introduced into the coating chamber, and the polymeric coating solution is sprayed on the air-suspended bicarbonate crystallites, until the coating weight is about 30% of the total dry weight of the coated particles. The procedure is repeated, except that Hydroxypropylmethylcellulose (Methocel 60 HG, Dow Chemical Co.) is employed as the hydrophilic polymer. The procedure is repeated, except that maltodextrin (Lodex 10; Durkee Foods) or amylodextrin is employed as the water-soluble polymer, and 0.5 g of a surfactant is included in the solution (polyoxyethylenesorbitan monolaurate; Tween 20; ICI Americas, Inc.).

The procedure is repeated except that an 80/20 by weight mixture of polyvinylpyrrolidone/ polyvinyl acetate is employed as the crystallite- coating polymer ingredient. The coated particles consist of a continuous polymer film coating on an inner core of a single crystallite or multiple crystallites of sodium bicarbonate.

26

EXAMPLE III This Example illustrates the effectiveness of an encapsulated slow-release pre-emergence herbicide in accordance with the present invention.

Parts hexazinone (Velpar) 15

NH₄HC0₃ 100 κ₂co₃ 100 guar gum 50 ethoxylated sorbitan monolaurate 30 ethanol 120

Following the procedure of Example I, the NH₄HC0₃ and K₂C0₃ salts are suspended in an ethanol solution of the hexazinone and guar gum ingredients. The solvent is removed, and the resultant dry powder has a continuous film coating of hexazinone/guar gum on the surface of the inorganic salt particles.

The prepared powder is blended with the ethoxylated sorbitan monolaurate ingredient, and the blend is suspended in water to form an aqueous emulsion.

The emulsion formulation is diluted with water to 250 ppm of herbicide ingredient. The diluted formulation is tested at the rate of 10 pounds per acre of herbicide ingredient, by drenching the formulation onto soil disposed in 4.5 inch plastic pots which contain respectively weed seeds of velvet leaf, jimsonweed, tall morningglory, switchgrass, barnyard grass, and green foxtail. The percent control of each weed type is determined two weeks after treatment in comparison with untreated controls. The results indicate essentially 100 percent control of each weed type germination.

EXAMPLE IV This Example illustrates the preparation of an encapsulated fungicide powder.

Parts

Captan 5

NaHC0₃ ^(1> 40 polyethylene glycol (M.W. 4000) 10

Following the procedure of Example I, the NaHC0₃ salt is suspended in a dioxane solution of the Captan and polyethylene glycol ingredients. The solvent is removed, and the resultant powder consists of inorganic salt particles encapsulated with a continuous film coating of Captan/ polyethylene glycol on the surface of the particles. The coating on the particles is about 30 weight percent, based on the weight of encapsulated particles.

The encapsulated particles have an average particle size of about 80 microns. A portion of the powder is granulated by spraying the powder with water, mixing the powder in a rotary mixer, and then drying the granulated product.

^(1> 3 DF; Church & Dwight Following the procedure described above, a second encapsulated fungicide powder composition is prepared by substituting pentachloronitrobenzene (TERRACLOR FF; Uniroyal Chemical Co.) for the Captan ingredient.

Claims

WHAT IS CLAIMED IS:

1. A slow-release powder composition composed of encapsulated particles which are a combination of ingredients comprising (1) a particulate inorganic salt ingredient selected from the group consisting of alkali metal and ammonium bicarbonates; and (2) a blend ingredient comprising (a) an agrochemical compound, and (b) a water-soluble or water-dispersible hydrophilic organic polymer; wherein the blend ingredient is in the form of a continuous film coating on the surface of the inorganic salt particles, and the blend ingredient coating functions as a slow-release medium in the presence of moisture.

2. A composition in accordance with claim 1 wherein the average particle size of the inorganic salt ingredient is in the range between about 1-180 microns.

3. A composition in accordance with claim 1 wherein the average particle size of the inorganic salt ingredient is in the range between about 200-800 microns.

4. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises sodium bicarbonate.

5. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises potassium bicarbonate.

6. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises ammonium bicarbonate.

7. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises sodium bicarbonate and potassium bicarbonate.

8. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises sodium bicarbonate and ammonium bicarbonate.

9. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises potassium bicarbonate and ammonium bicarbonate.

10. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises sodium bicarbonate, potassium bicarbonate and ammonium bicarbonate.

11. A composition in accordance with claim 1 wherein the inorganic salt ingredient includes between about 0.5-20 weight percent of at least one compound selected from the group consisting of alkali metal and ammonium carbonates, based on the weight of inorganic salt ingredient.

12. A composition in accordance with claim 1 wherein the blend ingredient coating on the surface of the inorganic salt particles comprises between about 5-70 weight percent of the dry particle weight.

13. A composition in accordance with claim 1 wherein the agrochemical compound in the blend ingredient coating comprises between about 0.5-35 weight percent of the coating weight.

14. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises a fungicide.

15. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises a herbicide.

16. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises an insecticide.

17. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises a plant growth regulator.

18. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises a fertilizer.

19. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises at least two biologically active organic compounds.

20. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is a polysaccharidic derivative.

21. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is a hydrocolloid.

22. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is a starch derivative.

23. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is maltodextrin or amylodextrin or a mixture thereof.

24. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is a polyhydroxy or polyoxyalkylene derivative.

25. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is polyalkylene glycol.

26. A composition in accordance with claim 1 wherein the continuous film-forming component of the surface coating on the particles is a hydrophilic polymer having a content between about 0.5-40 weight percent of a water-insoluble polymer, based on the coating weight.

27. An agrochemical formulation which is a dry blend of at least two powder compositions in accordance with claim 1.

28. An aqueous agrochemical formulation which contains a dispersed phase of a slow-release powder composition in accordance with claim 1.

AMENDED CLAIMS

[received by the International Bureau on 15 April 1996 (15.04.96), original claims 11,12 and 26 amended; remaining claims unchanged (2pages)]

10. A composition in accordance with claim 1 wherein the content of inorganic salt ingredient comprises sodium bicarbonate, potassium

5 bicarbonate and ammonium bicarbonate.

11. A composition in accordance with claim 1 which additionally includes between about 0.5-20 weight percent of at least one compound selected from the group consisting of alkali metal

10 and ammonium carbonates, based on the weight of inorganic salt ingredient.

12. A composition in accordance with claim 1 wherein the blend ingredient coating on the surface of the inorganic salt particles comprises

15 between about 5-70 weight percent of the dry encapsulated particle weight.

13. A composition in accordance with claim 1 wherein the agrochemical compound in the blend ingredient coating comprises between about

20 0.5-0.35 weight percent of the coating weight.

14. A composition in accordance with claim 1 wherein the agrochemical ingredient comprises a fungicide. 22. A composition in accordance with claim 1 wherein the surface coating polymer on the particles is a starch derivative.

26. A composition in accordance with claim 1 wherein the surface coating hydrophilic polymer has a content between about 0.5-40 weight percent of a water-insoluble polymer, based on the coating weight.