TECHNICAL FIELD

[0001 ] The present invention relates to a fertiliser coating that contains a poorly water- soluble active compound. More particularly, in addition to containing a poorly water- soluble active compound, the fertiliser coating of the present invention suppresses dust formation.

BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] In addition to fertilisers, plants often require additional active compounds, for example fungicides, to support growth. Use of fungicides is known as being an effective method to treating a range of soil-borne diseases for a variety of crops, such as canola, wheat and barley. Fungicides, along with many other active compounds are poorly soluble in water and so the application techniques are limited. Fungicides and other poorly water-soluble active compounds are typically formulated into a water-based suspension concentrate and then added into the soil by way of a range of methods. For example, the suspension concentrate can be mixed into liquid fertilisers, coated onto seeds or coated onto particulate fertilisers. Of these methods, the coating of particulate fertilisers is the most common. During the coating application, a suitable coating rate is specified so as to achieve the minimum effective fungicide field rate.

[0004] Annual rainfall has been gradually declining in certain geographical areas, resulting in lower crop yields. In response to declining yields, growers have reduced their nutrient (fertiliser) inputs. However, as the minimum effective fungicide field rate remains constant, there is a higher ratio of fungicide to the fertiliser. The increased amounts of the water-based fungicide suspension concentrate being added to the fertiliser increases the water content of the final coated product. The increased water content degrades the fertiliser granule, causing break down of the granule and leading to fragmentation and dusting.

[0005] The design of water-based suspension concentrate formulations traditionally focuses on ease of manufacture, storage, handling and application but there has been little thought to the above discussed long term quality problems, such as fragmentation and dusting. Indeed, the only current solution to the problem of which the inventors are aware is to increase the strength of the suspension concentrates, thereby reducing the water content. Higher strength water-based suspension concentrates however create coating application problems.

[0006] Anti-dusting agents are used in a wide variety of industries where dusts cause occupational health problems. They are also used in fertiliser applications to suppress the fine, persistent, dusts that are released when product is handled. The anti-dusting agents act by being sticky, and thereby re-attach the dust particles back onto the granule. Some anti-dusting agents further act by sealing the granule and reduce dust re-generation over time.

[0007] Whilst anti-dusting agents are effective in suppressing dust, they also stick the fertiliser to the handling equipment used to load and unload trucks. This may cause blockages in the equipment, slowing the loading process. Many anti-dusting agents can also be slow to dry or cure, and so the treated granule cannot be transported or used immediately. This requires further handling and causes despatching problems. This problem is exaggerated when a fungicide is added as the combination of products further slows the drying process and causes greater delays in the despatching of fertiliser.

[0008] Furthermore, some existing anti-dusting agents are viscous and require heating and specialised application equipment to spray it onto fertiliser granules.

[0009] It is against this background that the present invention has been developed.

[0010] The present invention seeks to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above, or to provide the consumer with a useful or commercial choice. [001 1 ] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

SUMMARY OF INVENTION

[0012] In accordance with the present invention, there is provided a coating composition for applying a poorly water-soluble active compound to granules of a fertiliser, the coating composition comprising an emulsion comprising an aqueous phase and a nonaqueous phase, wherein the poorly water-soluble active compound is suspended in the aqueous phase, and a water-soluble adhesive agent is dissolved in the aqueous phase.

[0013] Throughout this specification, unless the context requires otherwise, the term "poorly water-soluble", will be understood to refer to solid compounds that have water solubility of less than 3000 mg/L. In one form of the present invention, the water solubility of the poorly water-soluble active compound is less than 3000 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 2500 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 2000 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 1500 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 1000 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 500 mg/L. In an alternative form of the present invention, the water solubility of the poorly water-soluble active compound is less than 300 mg/L.

[0014] The inventors have found that the coating composition of the present invention allows for the application of the poorly water-soluble active compound to the fertiliser granules, whilst limiting the amount of fragmentation of the fertiliser granule post application. It is understood that the inclusion of the water-soluble adhesive agent allows for the bonding of the dispersed poorly water-soluble active compound to the fertiliser granule, whilst simultaneously lowering the amount of water required in the final composition. The low water content of the coating composition has been found to reduce the amount of fragmentation of the coated fertiliser granule. Furthermore, the inventors have found that the inclusion of a non-aqueous phase as an emulsion in the aqueous phase prevents the coating composition from drying out and becoming brittle. It has been found that the non-aqueous phase imparts a level of pliability to the coating composition, making the coated fertiliser granule less susceptible to damage caused by impacts during handling. The reduction in fragmentation and the resistance to damage of the coating composition has been found to result in a coated fertiliser granule that has reduced dusting effects.

[0015] As the surface does not readily dry out, the water-soluble adhesive agent remains viscid. The inventors have found that this is advantageous as the viscid coating further acts to supress dust formation by providing a surface for dusted particles to adhere to.

[0016] Without wishing to be bound by theory, the inventors have found that once the coating composition has been applied to the fertiliser granule, the coating composition acts to retard the ingress of water into the fertiliser granule. This is primarily attributed to the hydrophobic nature of the non-aqueous phase that is emulsified throughout the coating composition. Additionally, the coating composition prevents the water moving out of the granule. This is understood by the inventors to reduce the amount of salts that are carried to the fertilisers' surface, thereby preventing the surface from drying out and reducing the rate of degradation of the fertiliser granule.

[0017] In one form of the present invention, the coating composition contains between 10 and 60 weight% water. Alternatively, the coating composition contains between 15 and 55 weight% water. Alternatively, the coating composition contains between 15 and 50 weight% water. Alternatively, the coating composition contains between 15 and 45 weight% water. Alternatively, the coating composition contains between 15 and 40 weight% water. Alternatively, the coating composition contains between 20 and 40 weight% water. Alternatively, the coating composition contains between 25 and 40 weight% water. Alternatively, the coating composition contains between 30 and 40 weight% water. Alternatively, the coating composition contains between 35 and 40 weight% water.

[0018] In alternative form of the present invention, the coating composition comprises less than 60 weight% water. Alternatively, the coating composition comprises less than 55 weight% water. Alternatively, the coating composition comprises less than 50 weight% water. Alternatively, the coating composition comprises less than 45 weight% water. Alternatively, the coating composition comprises less than 40 weight% water. Alternatively, the composition comprises less than 35 weight% water. More preferably, the composition comprises less than 30 weight% water.

[0019] Without wishing to be bound by theory, the inventors have found that the low water content of the coating composition of the present invention significantly reduces the amount of fragmentation of the fertiliser granule, leading to reduced dusting.

[0020] As would be understood by a person skilled in the art, a suspension is a mixture between two substances, one of which is finely divided and dispersed in the other.

[0021 ] As would be understood by a person skilled in the art, particle size distributions are often measured by laser diffraction analysis, and expressed using D values. The meanings of the respective D values, are:

D10: size under which 10 % of the particles are below by volume;

D50: size under which 50 % of the particles are below by volume, representing the mean particle size; and

D90: size under which 90 % by volume of the particles are below by volume.

[0022] In one form of the present invention, the mean particle size of the poorly water- soluble active compound between 1 and 50 μιη. The inventors have found that the control of the particles size of the poorly water-soluble active compound can be used to improve the distribution and coverage of the poorly water-soluble active compound over the fertiliser granule. Without wishing to be bound by theory, the inventors have found that the finer the particle size of the poorly water-soluble active compound, the more particles that can be spread over each fertiliser granules surface and a more even coating can be achieved. This enables a more consistent distribution of the poorly water-soluble active compound over a large number of fertiliser granules, which results in a controlled distribution of the poorly water-soluble active compound to the soil. Additionally, the inventors have found that finer poorly water-soluble active compound particles improve the adhesion of the poorly water-soluble active compound to the fertiliser granule. Without wishing to be bound by theory, it is understood that the reduced particles size leads to an increased van der Waals forces. It is understood by the inventors that at particles sizes above the 50 μιη the larger particles begin to impact the handling properties of the composition would be compromised.

[0023] Finer poorly water-soluble active compound particles also improve the efficacy of the poorly water-soluble active compound. As would be appreciated by a person skilled in the art, for a given mass, the smaller the particle size the larger the reactive surface area, leading to higher rates of dissolution in the soil. Without wishing to be bound by theory, the inventors understand that as the particles size exceed 50 μιη the efficacy of the active compound would be reduced to an impractical extent.

[0024] Preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 40 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 30 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 20 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 15 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 10 μιη. Still preferably, the mean particle size of the poorly water- soluble active compound is between 1 and 9 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 8 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 7 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 6 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is between 1 and 5 μιη.

[0025] Alternatively, the mean particle size of the poorly water-soluble active compound is preferably less than 50 μιη. More preferably, the mean particle size of the poorly water-soluble active compound is less than 45 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 40 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 35 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 30 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 25 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 20 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 15 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 10 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 9 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 8 μιη. Still preferably, the mean particle size of the poorly water- soluble active compound is less than 7 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 6 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 5 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 4 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 3 μιη. Still preferably, the mean particle size of the poorly water- soluble active compound is less than 2 μιη. Still preferably, the mean particle size of the poorly water-soluble active compound is less than 1 μιη.

[0026] In one form of the present invention, the D90 of the poorly water-soluble active compound is preferably less than 50 μιη. More preferably, the mean particle size of the poorly water-soluble active compound is less than 45 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 40 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 35 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 30 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 25 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 20 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 15 μιη. Still preferably, the D90 of the poorly water-soluble active compound is less than 10 μιη.

[0027] The poorly water-soluble active compound can be any water insoluble, agriculturally active ingredient. In one form of the present invention, the poorly water- soluble active compound is selected from one or more of fungicides, insecticides, herbicides and nutrient concentrates.

[0028] In one form of the present invention, the poorly water-soluble active compound contains an active ingredient selected from the group comprising: diazole-, triazole-, phenylpyrrole-, strobilurin-, carboxamide-, carbamate-, anilinopyrimidine-, phenoxyquinoline-, benzimidazole-, systemic- and phenylamide fungicides.

[0029] Where the poorly water-soluble active compound is a fungicide, the fungicide contains an active ingredient selected from the group comprising: fludioxonil, difenconazole, mefenoxam, azoxystrobin, trifloxystrobin, propiconazole, myclobutanil, captan, thiram, carboxin, oxycarboxin, imazalil, tebuconazole, mancozeb, maneb, pentachloronitrobenzene, streptomycin, thiabendazole, thiophanate-methyl, cypermethrin, sedaxane, fluquinconazole, imidacloprid, fluxapyroxad, ipconazole, penflufen, prothioconazole, triflumuron, imidacloprid, triadimenol, triticonazole, fluquinconazole, ipconazole, imidacloprid, triadimefon, metalaxyl, and triadimenol.

[0030] In preferred form of the present invention the active ingredient of the poorly water-soluble active compound is flutriafol.

[0031 ] As would be understood by a person skilled in the art, nutrient concentrates are suspension concentrates composed of nutrients in insoluble forms. Such nutrients include zinc, copper, manganese, molybdenum, magnesium, calcium, cobalt, nickel, iron, sulfur, selenium and boron.

[0032] Preferably, the coating composition contains between 8 and 85 weight% poorly water-soluble active compounds. More preferably, the coating composition contains between 22 and 62 weight% poorly water-soluble active compounds. Still preferably, the coating composition contains about 35 weight% poorly water-soluble active compound. Without wishing to be bound by theory, it is understood by the inventors that outside of the above ranges, the effectiveness of the coating composition is decreased. Less than 8 weight% poorly water-soluble active compounds requires too much coating composition to be applied to a fertiliser in order to achieve minimum effective field rate. Greater than 85 weight% and the ratio of the poorly water-soluble active compounds to the remainder of the coating composition becomes too great to ensure effective adherence.

[0033] Preferably, the concentration of the poorly water-soluble active compound is between 100 and 1000 g/L. More preferably, the concentration of the poorly water- soluble active compound is between 200 and 750 g/L. Still preferably, the concentration of the poorly water-soluble active compound is about 400 g/L.

[0034] As would be understood by a person skilled in the art, an emulsion is mixture of two substantially immiscible substances in liquid form, in which small regions of one substance are suspended in the other substance. In the present invention, droplets of the non-aqueous phase are suspended within and dispersed throughout the aqueous phase. The inventors have found that the emulsion of the non-aqueous phase in the aqueous phase is required for a suitable coating composition. Without the emulsion, the non-aqueous phase and the aqueous phase will separate and the coating composition will form large distinct fractions. This will prevent the poorly water-soluble active compound from being applied evenly across the fertiliser granules. This means that some areas will get over-applied, with possible toxic effects, whilst other areas will be under-applied, with insufficient concentrations for the active compound to be effective.

[0035] In one form of the present invention, the non-aqueous phase more specifically comprises one or more fatty acids. Preferably, the fatty acids are liquid at ambient temperature. More preferably, the liquid fatty acids are selected from saturated, unsaturated or polysaturated liquid fatty acids.

[0036] As would be understood by a person skilled in the art, fatty acids are carboxylic acids with aliphatic carbon chains. The aliphatic carbon chains can be saturated, or mono-, di- or poly unsaturated. The chain length can vary from two carbon atoms up to over 28. Whilst a saturated liquid fatty acid has a limited geometric configuration, a greater variety of geometric configurations are possible with unsaturated liquid fatty acids. Without wishing to be bound by theory, the inventors have determined that the suitability of any of the multitude of possible liquid fatty acids or mixtures of liquid fatty acids is dependent on the required hydrophile-lipophile balance (HLB) of the liquid fatty acid or mixture thereof. As would be understood by person skilled in the art, all emulsifiers have a hydrophilic (water) and a lipophilic (fat/oil) component and the balance between the two is referenced by the HLB. All fats and oils have a required HLB, which the emulsifier needs to match in order to make it miscible in water.

[0037] In one form of the present invention, the required HLB range of the one or more liquid fatty acids is between 3 and 10. Preferably, the required HLB range of the one or more liquid fatty acids is between 6 and 10. More preferably, the required HLB range of the one or more liquid fatty acids is between 6 and 8. It is understood by the inventors that the control of the required HLB of the one or more liquid fatty acids ensures that phase separation of the coating composition does not occur. In addition, use of liquid fatty acids with a required HLB outside the range of 3-10 will have other undesirable physical properties, such as the viscosity of coating composition and the viscidity of the coating following application. Drying time can also be too fast or too slow once the poorly water-soluble active compound is coated with the composition. [0038] Preferably, the coating composition contains between 0.2 and 21 weight% nonaqueous phase. More preferably, the coating composition contains between 2 and 15 weight% non-aqueous phase. Still preferably, the coating composition contains between 3 and 14 weight% non-aqueous phase. Still preferably, the coating composition contains between 3 and 13 weight% non-aqueous phase. Still preferably, the coating composition contains between 3 and 12 weight% non-aqueous phase. Still preferably, the coating composition contains between 3 and 1 1 weight% non-aqueous phase. Still preferably, the coating composition contains between 3 and 10 weight% non-aqueous phase. Without wishing to be bound by theory, it is understood by the inventors that outside of the above ranges, the effectiveness of the coating composition is decreased. Less than 0.2 weight% non-aqueous phase results in a surface coating that dries out and becomes too brittle to be effective. Greater than 21 weight% and the ratio of the non-aqueous phase to the remainder of the coating composition becomes too great to ensure effective adherence.

[0039] In one form of the present invention, the water-soluble adhesive agent comprises one or more soluble carbohydrates. More preferably, the one or more soluble carbohydrates are sugars. Still preferably, the one or more sugars are selected from mono-saccharides, disaccharides and poly- and oligo- saccharides.

[0040] In one form of the present invention, the water-soluble adhesive agent comprises at least 25% sucrose. Preferably, the water-soluble adhesive agent comprises at least 30% sucrose. More preferably, the water-soluble adhesive agent comprises at least 35% sucrose. Still preferably, the water-soluble adhesive agent comprises at least 40% sucrose. Still preferably, the water-soluble adhesive agent comprises at least 45% sucrose. Still preferably, the water-soluble adhesive agent comprises at least 50% sucrose.

[0041 ] In one form of the present invention, the water-soluble adhesive agent is molasses. As would be understood by a person skilled in the art, molasses is a byproduct of refining organic materials, such as sugarcane into sugar. In processing of the organic material, sugar is removed by successive stages of evaporation, crystallisation and centrifugation. The dark, sugar rich syrup obtained at the end of the process is molasses. As the syrup can be taken from any stage of the refining process, different grades of molasses are possible. Molasses is normally 50% sucrose, with other minor components such as glucose, fructose, and raffinose being present. The more complex oligo- and polysaccharides are present at concentrations of 1 % or less. As would be understood by a person skilled in the art, the grades of molasses and their names vary between different countries. Standard grades include (in order or extraction): light (US Grade A), dark (US Grade B) and Bootstrap (US Grade C). Preferably, the molasses is dark grade. The inventors believe that the sugar content of the light fraction may be too high, which could possibly lead to a less viscous final product. The viscosity of the Bootstrap grade on the other hand is too high, leading to mixing difficulties. Bootstrap grade is also understood to contain impurities which may impact long term use.

[0042] Preferably, the coating composition contains between 0.4 and 31 weight% the water-soluble adhesive agent. More preferably, the coating composition contains between 6 and 25 weight% the water-soluble adhesive agent. Still preferably, the coating composition contains about 21 weight% the water-soluble adhesive agent. Without wishing to be bound by theory, the inventors believe that at the lower ranges there is insufficient water-soluble adhesive agent to have any effect on suppressing dusts. At the higher ranges, the high concentrations of water-soluble adhesive agents makes the product very viscous making it unsuitable for coating.

[0043] In one form of the present invention, the composition contains one or more fatty acid esters. It is understood by the inventors that the one or more fatty acid esters in the coating are reaction products of the one or more sugars in the water-soluble adhesive agent and the liquid fatty acid of the non-aqueous phase. As would be understood by a person skilled in the art, fatty acid esters are naturally forming non- ionic surfactants consisting of sucrose as the hydrophilic group and the fatty acid as the lipophilic group. These fatty acid esters can have a range of required HLB from 1 -16 depending on the sugar/fat combination. Preferably, the one or more fatty acid esters have a range of required HLB from 3-16. More preferably, the one or more fatty acid esters have a range of required HLB from 6-10.

[0044] Preferably, the coating composition contains between 2.8 and 8.4 weight% fatty acid esters.

[0045] In one form of the present invention, the coating composition further comprises one or more surfactants. Preferably, the one or more surfactants are non-ionic. More preferably, the one or more surfactants are selected from the group comprising: alkyl benzene sulphonates; naphthalene sulphonates; alkyl naphthalene sulphonates and lignosulfonates.

[0046] The surfactants are used within the coating composition to emulsify the one or more liquid fatty acids and the one or more fatty acid ester. The one or more surfactants therefore need to emulsify a fatty acid that has a required HLB of 6-10 or fatty acid ester that has a required HLB of 3-16.

[0047] Preferably, the coating composition contains between 0.1 and 5 weight% of the one or more surfactants. If the surfactant concentration is too low, then the emulsion stability is effected and thickening occurs. Conversely, high or excessive levels of surfactant creates foaming issues and adds an unnecessary cost.

[0048] In one form of the present invention, the coating composition further comprises an anti-foaming agent. Preferably, the anti-foaming agent is a polymer. More preferably, the anti-foaming agent is silicone based. Still preferably, the anti-foaming agent is polysiloxane.

[0049] Preferably, the coating composition contains between 0.02 and 7 weight% anti- foaming agent. More preferably, the coating composition contains between 0.5 and 4 weight% anti-foaming agents. Still preferably, the coating composition contains about 0.2 weight% anti-foaming agents. As would be understood by a person skilled in the art, anti-foaming agents are chemical additives that reduces and hinders the formation of foams. The amount of anti-foaming agent required is heavily dictated by the components of the coating composition and the process in which they are combined. S would be understood by a person skilled in the art, the anti-foaming agent is typically added to a concentration that controls any foaming issues that arise during manufacture of the coating composition.

[0050] In one form of the present invention, the coating further comprises one or more biocides. Preferably, the biocides are selected from the group comprising symtriazine based biocides and microbiocides based upon isothiazolones. A preffered symtriazine based biocide is 2,2',2"-(hexahydro-1 ,3,5-triazine-1 ,3,5-triyl) triethanol. A preffered microbiocides based upon isothiazolones is 1 ,2-benzisothiazol-3(2H)-one. Still preferably the coating comprises both a symtriazine based biocide and a microbiocide based upon isothiazolones. [0051 ] Preferably, the coating composition contains between 0.02 and 1 weight% biocides. More preferably, the coating composition contains between 0.02 and 0.75 weight% biocides. More preferably, the coating composition contains between 0.02 and 0.5 weight% biocides. More preferably, the coating composition contains between 0.02 and 0.25 weight% biocides.

[0052] In one form of the present invention, the coating further comprises one or more dispersing and one or more wetting agents. Preferably, the dispersing and wetting agents are selected from the group comprising sodium salt of a naphthalene sulfonate condensate, sodium alkyl naphthalene sulfonate blends and polyoxylated butyl ether.

[0053] Preferably, the coating composition contains between 0.02 and 7 weight% dispersing and wetting agents. More preferably, the coating composition contains between 0.5 and 4 weight% dispersing and wetting agents. Still preferably, the coating composition contains about 2 weight% dispersing and wetting agents. Preferably, the ratio of dispersants to wetters is about 2:1

[0054] As would be understood by a person skilled in the art, wetting and dispersing agents are used to assist in the dispersion of solid particles throughout a liquid. Wetting is the first step in the dispersion process. The air that surrounds the solid particles must be substituted by liquid. Wetting will take place when the surface tension of the liquid is low compared to the surface energy of the solid particles. Wetting will not occur when the surface tension of the liquid is too high. In that case, the surface tension of the liquid can be lowered by adding a wetting agent. Without wishing to be bound by theory, the wetting agent will absorb on the solid particles and orient on the liquid-air interface. The second step in the dispersion process is to maintain the separation of the dispersed solid particles to prevent flocculation. The functionality of a dispersing agent is to prevent flocculation. Without wishing to be bound by theory, the dispersing agent will adsorb on the solid-liquid interface and assure repulsion between the particles. This repulsion typically results from electrostatic stabilisation and/or steric stabilisation.

[0055] In one form of the present invention, the coating further comprises one or more colourants. Preferably, the colourants are selected from one or more water dispersible pigments and dyes. [0056] In one form of the present invention, the coating composition further comprises a thickener. Preferably, the thickener is a shear thinning thickener and can be a montmorillonite clay (bentonite or attapulgite) or natural gum. More preferably, the thickener is a natural gum such as xanthan. Still preferably, the coating composition the coating composition contains less than 0.3 weight percent thickeners.

[0057] Preferably, the coating composition contains between 0.01 and 1 weight% anti- foaming agent. More preferably, the coating composition contains between 0.01 and 0.75 weight% anti-foaming agents. Still preferably, the coating composition contains between 0.01 and 0.5 weight% anti-foaming agents. Still preferably, the coating composition contains between 0.01 and 0.25 weight% anti-foaming agents. Still preferably, the coating composition contains between 0.01 and 0.1 weight% anti- foaming agents. The coating composition of the present invention is suitable to be applied to granular fertilisers. Preferably, the granular fertiliser is selected form the group: Urea, NP, NK, NKS and NPKS type granular fertilisers.

[0058] In one form of the present invention, the viscosity of the coating composition is between 800 - 3,000 cP. As would be appreciated by a person skilled in the art, a number of the components of the coating composition contribute to the final viscosity of the coating composition.

[0059] As would be appreciated by a person skilled in the art, the viscosity of the coating composition affects the storage and usability of the coating composition. If the viscosity is too low, then the poorly water-soluble active compound particles begin to settle at a faster rate and the product has a shorter shelf-life. Conversely, if the viscosity is too high, then handling characteristics such as pourability are affected, so it becomes difficult to drain drums and tanks which leads to higher product losses. A thick product is harder to stir/mix and it is harder maintain product consistency in storage containers. A thick product is harder to pump and spray, requiring higher duty and more expensive equipment. As would be understood by person skilled in the art, the coatings are usually applied to fertiliser granules by spraying onto a conveyor or into a mixing device such as a blender or coating drum. To apply a viscous liquid, heavy duty pumping equipment is required and the application onto fertilisers is poor. Similarity, a more viscous product is harder to manufacture and adds more cost to the final product. [0060] Viscosity is also important for its ability to coat fertiliser granules consistently. With increased viscosity there is decreased flowability and the consistency and quality of the coating application is poorer.

[0061 ] The major contributor to the viscosity of the coating composition is the combination of the water-soluble adhesive agent and the non-aqueous phase. The higher the ratio of these components to the aqueous phase, the more viscous the coating composition is. The inventors have found that the increase in viscosity is the major limitation on the amount of the water-soluble adhesive agent and the nonaqueous phase that can be incorporated into the coating composition. Once the water content becomes too low, the coating composition would be too viscous to be practicable.

[0062] The concentration of the poorly water-soluble active compound also directly impacts the final viscosity. As the concentration of poorly water-soluble active compound increases the viscosity of the coating composition increases. Furthermore, as the particle size decreases, viscosity also increases as there is a larger surface area of particles in contact with each other. This increase in viscosity can be countered to an extent by the type of wetting/dispersing agents that are used and the concentration they are used at. The finer the particle size of the poorly water-soluble active compound, the higher the concentration of the wetting/dispersing agents that are required.

[0063] The inventors have also found that the stability of the emulsion affects the viscosity of the final product. The surfactants are typically used to stabilise the emulsion but the wetting/dispersing agents added to the composition have an extra stabilising effect.

[0064] In accordance with a second aspect of the present invention, there is provided a method of preparing a coating composition for applying a poorly water-soluble active compound to granules of a fertiliser, the method comprising the step of: mixing an aqueous phase, a non-aqueous phase, a water-soluble adhesive agent and the poorly water-soluble active compound.

[0065] In one form of the present invention, the components of the coating composition are combined in a mixing vessel. [0066] Preferably, the aqueous phase, the non-aqueous phase and the water-soluble adhesive agent are initially mixed together to produce a coating base, the poorly water- soluble active compound is then added to the coating base. Preferably, the poorly water-soluble active compound is added to the coating base during agitation of the coating base.

[0067] In one form of the present invention, where the coating composition contains one or more colorants, the colourants are added to the aqueous phase, prior to the addition of the non-aqueous phase and the water-soluble adhesive agent.

[0068] In one form of the present invention, where the coating composition contains one or more surfactants, the surfactants are added to the coating base prior to the addition of the poorly water-soluble active compound.

[0069] In one form of the present invention, where the coating composition contains one or more biocides, the biocides are added to the coating base prior to, simultaneously to, or after the addition of the poorly water-soluble active compound.

[0070] In form of the present invention, where the coating composition contains one or more thickeners, the thickeners are added to the coating base after the addition of the poorly water-soluble active compounds.

[0071 ] In form of the present invention, where the coating composition contains one or more dispersant and wetting agents, the dispersant and wetting agent are added to the coating base prior to the addition of the poorly water-soluble active compounds.

[0072] In one form of the present invention, the method further comprises the step of: milling the coating composition, following the addition of the poorly water-soluble active compound. Preferably the step of milling the coating composition reduces the particle size of the poorly water-soluble active compound.

[0073] In one form of the present invention, the step of milling the coating composition is preferably undertaken in a bead mill. Advantageously, the step of milling the coating composition improves the liquid stability (the finer the particles the less it settles), the finer the active ingredient the better activity it has and the finer the sizing, the better adhesion it has to fertiliser granules.

[0074] In form of the present invention, where the coating composition contains one or more thickeners, the thickeners are added to the coating base after the addition of the poorly water-soluble active compounds and preferably, after the step of milling the coating composition.

DESCRIPTION OF EMBODIMENTS

[0075] The present invention relates broadly to coating that provides for a poorly water- soluble active compound to be applied to granules of a fertiliser. Following the application of the coating to the fertiliser, the poorly water-soluble active compound is adhered to the fertiliser.

[0076] The coating composition of the present invention comprises an emulsion of an aqueous phase and a non-aqueous phase. The poorly water-soluble active compound is suspended in the aqueous phase. Whilst any water-insoluble, agriculturally active ingredient may be included in the coating composition of the present invention, the inventors have found it particularly useful for the purposes of coating the fertiliser granules with a fungicide, such as flutriafol.

[0077] Fungicides are typically formulated into a water-based suspension concentrate and then coated onto fertiliser granules. Typical water-based suspension concentrates have a high water content and that water absorbs into the granule upon coating. When the granule dries out, the migrating moisture carries with it salts that cause dusting of the granule. The dust component also has a high fungicide concentration, which creates potential health and safety problems with handling. The coating composition of the present invention has been formulated to reduce the dusting of fertilisers granule coatings.

[0078] As opposed to the above discussed water-based suspension concentrates, the coating composition of the present invention is based on a combination of a suspension concentrate and an aqueous emulsion. [0079] The non-aqueous phase comprises one or more liquid fatty acids. The inventors have found that the liquid fatty acids can either be mono- or poly- unsaturated, and have a required hydrophile-lipophile balance (HLB) between 6 and 10.

[0080] Suitable liquid fatty acids may be selected from the group comprising (required HLB shown in brackets): almond oil (6), anhydrous lanolin usp (10), apricot kernal oil (7), avocado (persea gratissima) oil (7), babassu oil (8), black currant oil (7-8), borage (borago officinalis) seed oil (7), brazil nut oil (8), canola oil (and) fragrance (7), canola oil (7), carrot (daucus carota sativa) root extract 6), carrot (daucus carota sativa) seed oil 6), ceresin (8), cetyl esters (10), cetyl esters wax nf (10), cetyl palmitate (10), cherry kernel oil 6), cocoa (theobroma cacao) butter 6), coconut (cocos nucifera) oil (8), cyclomethicone (7.5), diisopropyl adipate (9), dimethicone 5), dog rose (rosa canina) hips oil (7), emu oil (8), evening primrose (Oenothera biennis) oil (7), garcinia indica seed butter (8), generic essential oil (8), grape (vitis vinifera) seed oil (7), hazelnut oil (7), hemp (cannabis sativa) seed oil (7), hybrid safflower (carthamus tinctorius) oi), (9), jojoba (buxus chinensis) oil 6), karanja oil (8), kukui nut (aleurites moluccana seed) oil

(7) , lanolin (10), lanolin usp (10), macadamia (macadamia ternifolia) nut oil (7), mango (mangifera indica) seed butter (8), mango (mangifera indica) seed oil (7), meadowfoam seed oil 6-7), mineral oil (10), mineral oil nf (10), monoi de tahiti oil (8), myristyl myristate (8), neem oil (9), olive (olea europaea) oil (7), palm kernel flakes (8), palm oil

(8) , peach kernel oil (7), peanut oil nf 6), perilla seed oil (8), petrolatum (7), petrolatum usp (7), ppg-15 stearyl ether (7), pumpkin seed oil (8), red raspberry seed oil (7), retinyl palmitate 6), rice (oryza sativa) bran oil (7), rose hip oil (7), rosmarinus officinalis (rosemary) leaf ext), (7), safflower (carthamus tinctorius) oil (8), sea buckthorn 6-7), sesame (sesamum indicum) oil (7), sesame oil nf (7), shea oil (butyrospermum parkii) (8), shea butter (butyrospermum parkii) (8), soybean (glycine soja) oil (7), sunflower (helianthus annuus) seed oil (7), sweet almond (prunus amygdalus dulcis) (7), tamanu oil (8), tocopherol (vitamin e) (6), walnut oil (10-1 1 ), and wheat germ (trictum vulgare) oil (7).

[0081 ] The coating composition further comprises a water-soluble adhesive agent. The water-soluble adhesive agent acts to bind the coating composition to the fertiliser granule. Without wishing to be bound by theory, the binding of the coating composition to the fertiliser granule is thought to be a combined effect of the stickiness of the molasses, a thin film that forms over the granule and by changing the surface charge of the granule thereby promoting adhesion. A preferred water-soluble adhesive agent contains a mixture of mono-saccharides, di-saccharides and poly- and oligosaccharides. The inventors have determined that a suitable source of such a mixture of water-soluble adhesive agent can be found in molasses. As would be understood by a person skilled in the art, molasses is a viscous, dark and sugar-rich by-product of sugar extraction from the sugarcane {Saccharum officinarum L). In processing of the cane, sugar is removed by successive stages of evaporation, crystallisation and centrifugation. The dark, sugar rich syrup obtained at the end of the process is molasses. As the syrup can be taken from any stage of the refining process, different grades of molasses is possible. The molasses composition highly varies and depends on cane varieties, climate and processes.

[0082] Molasses is normally 50% sucrose, with other minor components such as glucose, fructose, and raffinose being present. The more complex oligo- and polysaccharides are present at concentrations of 1 % or less.

[0083] Though the major component of molasses is normally is sucrose, which is a di- saccharide, it is considered that the production process breaks a portion of the di- saccharide into mono-saccharides (glucose, fructose, galactose etc.) This means that mixtures of mono-saccharides, di-saccharides and possibly poly- and oligo- saccharides (as minor components) can be present.

[0084] When a mixture of saccharides is present as the water-soluble adhesive agent, the coating composition further comprises fatty acid esters. The fatty acid esters are a reaction product of the liquid fatty acids and the mixture of saccharides. Fatty acid esters, or sugar esters, are naturally forming non-ionic surfactants consisting of sucrose as the hydrophilic group and the fatty acid as the lipophilic group. These emulsifiers can have a range of required HLB from 1 -16 depending on the sugar/fat combination. Though a wide range of fatty acid esters are possible in the coating composition, it is preferred that the fatty acid esters have a required HLB of 6-10.

[0085] The coating composition of the present invention further comprises a non-ionic surfactant to emulsify the fatty acids and any other long chain reaction products within the coating composition. The only limitation on the choice of surfactant is that it must be matched with the particular required HLB of the liquid fatty acids. [0086] Anti-foaming agents may also be incorporated into the composition. Whilst a range of anti-foaming agents are suitable for use, the inventors have found that silicone based polymers such as polysiloxane are effective for use in the coating composition. As would be understood by a person skilled in the art, agitation and/or the mixing of surfactants will typically result in the generation of foam. This foam can get trapped within the liquid and cause high viscosities or they can be released and the foam makes mixing and filling of the product difficult. Sometimes the dispersants remove air from fine particles and this gets trapped in the liquid and causes high viscosities also. Anti- foaming agents rapidly spread over foamy surfaces (the air-liquid interface) where they destabilise the foam and this causes rupture of the air bubbles and breakdown of surface foam. Entrained air bubbles are agglomerated, and the larger bubbles rise to the surface of the bulk liquid more quickly. There are many types of defoamers but the silicon based ones are normally used for heavy duty applications.

[0087] Advantageously, one or more agricultural biocides may also be incorporated into the coating composition. The particular biocide selected for use will be dependant on the application, but symtriazine based biocides such as is 2,2',2"-(hexahydro-1 ,3,5- triazine-1 ,3,5-triyl) triethanol, and microbiocides based upon isothiazolones, such as 1 ,2-benzisothiazol-3(2H)-one are believed to be particularly useful.

[0088] The coating composition may further comprise one or more dispersing and wetting agents. Preferably, the dispersing and wetting agents are selected from the group comprising sodium salt of a naphthalene sulfonate condensate, sodium alkyl naphthalene sulfonate blends and polyoxylated butyl ether. As would be understood by a person skilled in the art, wetting and dispersing agents are a standard feature of suspension concentrate formulations. When powdered substances are mixed into water, the powdered substance tends to agglomerate and small lumps are deposited onto the bottom of the container. A dispersing agent is a surfactant which adsorbs onto the surface of the powder. This neutralises the surface charges on the powdered substance, which then allows the powder to freely disperse in water. The result is a fine, milky looking liquid with no settled agglomerates. The type of dispersing agent used is dependent upon the type of powder and its concentration is based upon the particle size and concentration of the powder. Advantageously, the dispersing agent has a secondary benefit of helping the powder attach onto the fertiliser granule by reducing the surface charges. [0089] The wetting agent works to give a similar overall effect to the dispersing agent. Wetting agents lower the surface tension of the liquid and allows the liquid to better coat the dispersing powders. This displaces any entrained air from the powder's surface, which aids in defoaming and also stabilises the product for particle's size reduction in the milling stage. When milling is undertaken, the air released can cause re-foaming and cause processing problems and poor quality finished product. The wetting agent also wets out the powder and help stabilise the powders in the suspension. Though the dispersing agents can do this really well on their own, this is not their primary job.

[0090] A major benefit of the wetting agent is that it improves the followability of the coating liquid over a surface (fertiliser granule) and results in a consistent and more even coating. The 'wetting' of the surfaces also creates stronger physical bonding of the powder to the surface which allows the powder to adhere better.

[0091 ] In order to produce the coating composition of the present invention, the inventors have determined that it is preferable to initially add the colourants to the water in the water and mix for 10 minutes to allow the colour to develop. Then combine at least the liquid fatty acids, the water soluble adhesive agents, the surfactants and the defoamer to form a coating base prior to the addition of the poorly water-soluble active compound. The components of the coating base are combined in a mixing vessel and allowed to combine for at least 10 minutes.

[0092] Without wishing to be bound by theory, the inventors understand that that the following reaction mechanisms occur during the preparation of the coating base:

The water-soluble adhesive agents will dissolve in the aqueous phase;

A portion of the water-soluble adhesive agents will react the liquid fatty acids to form a fatty acid ester phase

The surfactants and the fatty acid ester phase will form emulsions of the aqueous phase in the non-aqueous phase.

[0093] Biocides and anti-foaming agents are also preferably added to the coating base.

[0094] Once the components of the coating base have been sufficiently combined, the poorly water-soluble active compound is then added to the coating base. The poorly water-soluble active compound disperses throughout the aqueous phase, forming a suspension therein. It is advantageous to agitate the coating base whilst the poorly water-soluble active compound is added. If required, thickeners are also added to the mixture. The coating composition is then mixed for a further period time, typically at least 45 mins, to ensure complete combination.

[0095] The mixture then undergoes a milling/particle size reduction stage. This can be either by vertical or horizontal bead mill or some other wet-milling process. The sizing of the poorly water-soluble active compound normally starts at 40-50 microns and is milled down to 1 -5 microns. The milling process is required for a number of reasons: liquid stability (the finer the particles the less it settles), the finer the active ingredient the better activity it has and the finer the sizing, the better adhesion it has to fertiliser granules.

[0096] As would be understood by a person skilled in the art, particle size distributions are often measured by laser diffraction analysis, and expressed using D values. Throughout this specification, references to particle size distribution characteristics refer to characteristics measured by laser diffraction analysis.

[0097] The D50 value represents the median particle size. Median values are defined as the value where half of the sample by weight resides above this point, and half sample by volume resides below this point. The D50 is the size in microns that splits the distribution with half above and half below this diameter.

[0098] Particle Size Distribution was determined using the Mastersizer 2000 (Malvern, UK) laser diffractometer. The measurements were conducted using the dispersion unit

[0099] The intensity of the laser light registered on the particular detectors of the measurement system can be converted to particle size distribution according to the Mie Theory or the Fraunhofer theory. The choice of the theory is up to the performer of the measurements. The standard ISO 13320 recommends the application of the Mie Theory for particles smaller than 50 pm and for larger particles both theories provide similar results. The Fraunhofer model can predict the scattering pattern that is created when a solid, opaque disc of a known size is passed through a laser beam. However due to the sample nature very few particles are believed to be disc shaped and completely opaque and thus the Mie Theory was employed for measuring the particle size of the pulps. The Mie theory accurately predicts the light scattering behaviour of all materials under all conditions. The Mie Model predicts the way light is scattered through spherical particles and considers the way light passes through, or is absorbed by, the particle.

[00100] The Mastersizer 2000 measures samples in triplicate and reports the values as an average.

[00101 ] As discussed above, the high water content of typical water-based suspension concentrates degrades fertiliser granules, leading to a breakdown and eventual dusting of the granule. Advantageously, the coating composition of the present invention has low water content, thereby minimising water absorption into the granule. Further, the inclusion of the water-soluble adhesive agent and the liquid fatty acids makes the coating composition viscid. This helps adhere the poorly water- soluble active compound to the fertiliser granule. Though the coating compositions still contains an aqueous phase, the various water and mineral components seal the granule and restrict the movement of water and salts. The coating composition further acts to reduce dust generation as even when salts reach the surface of the granule, the viscid nature of the coating reduces the amount of particles that break off and become dusts.

[00102] The present invention is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally equivalent products, formulations and methods are clearly within the scope of the invention as described herein.

Example 1

[00103] An investigation into coating compositions with different strengths of the poorly water-soluble active compound has been undertaken to determine the effect this has on the amount of components required to produce a useful final coating composition. In this example, flutriafol was used as the poorly water-soluble active compound. Table 1 shows the components required to achieve flutriafol strengths form 100 - 1000 g/L.

Table 1

Example 2

[00104] The typical application rate of flutriafol is 400 g/L and so this composition was analysed further. The formulation of the 400 g/L coating composition was as follows:

[00105] The product had a viscosity of 1434 cP and a measured density of 1 .195 g/mL. The measured flutriafol concentration was 408.7 g/L. The D90 of the flutriafol was 15 μιη.

[00106] The dynamic viscosity is measured in Pascal seconds (Pa.s) which are the SI units. These are related to cPs (centipoise) which are non standard but also used. The viscosities were measured on a Brookfield Model LV viscometer using a LV3 spindle and a speed of 20 rpm. As would be appreciated by a person skilled in the art, Brookfield viscometers use a specific measurement technique. The viscometer rotates a sensing element in a fluid and measures the torque necessary to overcome the viscous resistance to the induced movement. This is accomplished by driving the immersed element, which is called a spindle, through a beryllium copper spring. The degree to which the spring is wound, indicated by the red pointer, is proportional to the viscosity of the fluid. The calculated shear rate, shear stress and viscosity are based on Newtonian liquid properties. When non-Newtonian liquids are studied it is possible to calculate the true shear rate, etc. by using the rotational speed and torque readings. The measuring system constants used to convert the rotational speed and torque to shear rate and stress are based on Newtonian liquids.

[00107] The coating composition was coated on a 1 kg fertiliser sample, using a pan granulator as the mixing/coating apparatus to determine the final fungicide concentration. The fertilisers were placed in the pan granulator and the liquid was sprayed onto the fertilisers using a plastic spray container. The amount of liquid applied was determined by weight loss of the container. The liquid dried in 10-20 seconds, depending upon the amount of liquid added and the granules had a mottled yellow appearance to them.

[00108] The results were as follows:

[00109] It is envisaged that the required amount of coating composition will be 1 .25 to 6.5 L per tonne of fertiliser, resulting in a fungicide concentration between 0.15% and 0.80% by weight of fertiliser.

[001 10] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. The invention includes all such variation and modifications. The invention also includes all of the steps, features, formulations and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.