Controlled-release active agents having biodegradable coatings

Abstract

Described herein are coated agricultural compositions comprising: an active agent; and a hard, hydrophobic coating surrounding the active agent, the coating comprising Portland cement and a fatty acid, optionally further comprising an additive selected from the group consisting of a biodegradable polymer and a biodegradable wax. Optionally, the fatty acid in the coating is between 15%-45% of the coating by weight. Further described herein according to embodiments, are methods for coating active agents comprising obtaining an active agent; and contacting the active agent with Portland cement and a fatty acid.

Description

CONTROLLED-RELEASE ACTIVE AGENTS HAVING BIODEGRADABLE COATINGSFIELD

[0001] Embodiments of the invention relate to compositions comprising controlled- release active agents having biodegradable coatings, comprising agricultural active agents such as fertilizer, pesticides, or nutritional agents.BACKGROUND

[0002] In the agricultural industry, many chemical compositions are provided to crops or to livestock to assist in the growing of the crops and livestock. For example, fertilizers are frequently administered during the growth of crops for promotion of plant growth and yield. Fertilizers comprising three macro nutrients, nitrogen (N), phosphorus (P), and potassium (K) are typically administered to crops. When administered together, these fertilizers are referred to as NPK fertilizers. Other nutrients such as calcium, magnesium, and sulfur, as well as micronutrients such as copper, iron, manganese, molybdenum, zinc, boron, silicon, cobalt and vanadium are also administered to plants during plant growth. Urea is a common chemical administered to plants as a source of nitrogen.

[0003] As many common fertilizers are water-soluble, excess fertilization and subsequent runoff into bodies of water may cause environmental problems. In order to allow more efficient administration of fertilizer, controlled-release fertilizers (CRF) have been developed, to provide release of the fertilizer over an extended period of time after administration to a crop. Such compositions may be useful to prevent loss of fertilizers by rain or irrigation, or to allow for fewer applications thereby leading to lower labor and equipment costs.

[0004] Although CRF may be advantageous to prevent over-fertilization and negative environmental impacts, substantial environmental downsides of using CRF remain. Currently many CRF are coated by various polymers, including microplastics which remain in the soil, occasionally for years after the administration of the fertilizer is complete. Microplastics are solid particles of plastic materials composed of mixture of polymers and functional additives. The European Regulation (Article 3(5) of Regulation (EC) No 1907 / 2006) definition for microplastics is: particles of certain dimension between 0.1 micron to 5 mm or fibers at the length of 0.3 to 15 mm and length to diameter ratio greater than 3. According to the regulation, no product containing 0.01% (w / w) shall be put intentionally in the EU market. This regulation severely limits the use of CRF containing materials which can be classified as microplastics.

[0005] In addition to CRF, controlled-release pesticides are used in agriculture. Pesticides are compositions which are administered in the vicinity of crops and other agricultural products to kill or limit the growth of a pest which negatively impacts the growth of the crop. The pest may be a plant such as a weed, or fungi, or insects. A pesticide which is used to limit the growth of a plant which negatively affects the crop, the pesticide is known as a herbicide.

[0006] Other controlled-release compositions used in agriculture include non-protein nitrogen (NPN) which is administered to livestock. As livestock typically require protein as part of their diet, an efficient way to provide protein to livestock such as ruminants is administration of non-protein nitrogen. Some examples of nitrogen-containing chemical compounds used for NPN include urea, biuret, and ammonia. Microbes in the livestock digestive system convert these nitrogen-containing compounds to compounds used to make protein. As NPN is typically less costly than plant-based protein, using NPN to replace some of the plant-based protein in ruminant diet provides an inexpensive method for increasing ruminant growth. As feeding NPN to livestock can release ammonia in the rumen, this may be potentially toxic to the livestock by elevating blood urea nitrogen levels. To avoid high concentrations of NPN in livestock diet, slow-release compositions comprising NPN have been developed to maintain a steady flow of NPN to livestock gut microbes without inducing ammonia-induced toxicity. An example of a commercial product comprising slow-release NPN is Optigen® by Alltech (Nicholasville, KY, USA).SUMMARY

[0007] Described herein, according to an embodiment, is a coated agricultural composition, comprising: an active agent; and a hard hydrophobic coating surrounding the active agent, the coating comprising Portland cement and a fatty acid.

[0008] Further described herein according to embodiments, are methods for coating active agents comprising: obtaining an active agent; and contacting the active agent with Portland cement and a fatty acid.DETAILED DESCRIPTION

[0009] Unless otherwise noted, technical terms are used according to conventional usage.

[0010] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The singular terms “a,” “an,” and “the” include plural referents unlesscontext clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The term “comprises” means “includes.” The abbreviation, “e.g.” is derived from the Latin exempli gratia and is used herein to indicate a non-limiting example. Thus, the abbreviation “e.g.” is synonymous with the term “for example.”

[0011] In case of conflict, the present specification, including explanations of terms, will control. In addition, all the materials, methods, and examples are illustrative and not intended to be limiting.

[0012] Terms:

[0013] Active agent: a chemical substance or biological agent which enhances agricultural production, whether in crops or livestock. An active agent may include a fertilizer, a pesticide, a nutrient or a seed.

[0014] Biodegradable Polymer: a polymer which readily undergoes fragmentation through degradation by microorganisms, photodegradation, oxidation, or hydrolysis, then bioassimilation of the polymer fragments by microorganisms, and subsequent mineralization. Preferably, the biodegradable polymer is a not soluble in water, Optionally, the biodegradable polymer is ethylcellulose. Optionally, the biodegradable polymer is poly (lactic acid) or chitosan.

[0015] Biodegradable Wax: A wax formed from vegetable oil by hydrogenation. Exemplary biodegradable waxes include but are not limited to soy wax, carnauba wax, cottonseed wax, palm wax, and castor wax.

[0016] Fatty acid: a carboxylic acid with an aliphatic chain. Fatty acid moieties are included within the definition of fatty acids.

[0017] Fertilizer: a composition administered to crops, typically to soil, to increase crop growth.

[0018] NPK: synthetic fertilizer comprising compounds or salts containing nitrogen, phosphorus, and potassium.

[0019] NPN: (non-protein nitrogen) a nitrogen-containing compound administered to animals such as ruminants, which the animal is capable of converting to protein. Urea, biuret and ammonia are common examples of NPN.

[0020] Pesticide: compositions which are administered in the vicinity of crops and other agricultural products to kill or limit the growth of a pest which negatively impacts the growth of the crop or agricultural product.

[0021] Portland Cement: a cement that hardens by reacting with water and forms a water-resistant product, comprising calcium silicates: tricalcium silicate (3CaO • SiO2), dicalcium silicate (2CaO • SiO2); and tricalcium aluminate (3CaO • AI2O3), and a tetra-calcium aluminoferrite (4CaO • AI2O3FC2O3). Portland cement may comprise additional materials such as iron oxides which impact the color of the Portland cement, and calcium sulfate.

[0022] Tall oil: a byproduct of wood pulp manufacture, comprising fatty acids.

[0023] Vegetable oil: Vegetable oils are oils extracted from seeds or other parts of edible plants.

[0024] Described herein, according to an embodiment, are novel compositions comprising a core having an active agent, preferably one used in agriculture, and a coating. The coating is formed by combining Portland cement with a fatty acid optionally in combination with additives such as biodegradable wax and / or biodegradable polymer. Preferably the fatty acid, before combination with Portland cement, is in liquid form. The combination forms an opaque, rigid, hydrophobic coating layer.

[0025] It has been surprisingly found by the inventor that compositions described herein are advantageous in that they demonstrate controlled / delayed release of agricultural active agents such as fertilizers, and are biodegradable, as they comprise coatings without synthetic polymers / plastics. They can serve as CRF, but have an advantage over current CRF in that no microplastics are formed when the compositions described herein are used in agricultural industries. In addition, the starting materials are based on natural minerals and are inexpensive. A primary ingredient in the coatings is Portland cement, which is readily available worldwide, and is an inexpensive raw starting material, used in the construction industry. Similarly, fatty acids can be used, including liquid fatty acids, such tall oil, which comprises free fatty acids and is a relatively inexpensive byproduct of the paper milling industry.

[0026] According to some embodiments, compositions described herein are capable of releasing not more than 15% of their active agent over the course of the first 24 hours when in contact with water. Optionally, compositions described herein are capable of releasing active agent over the course of greater than 30 days when in contact with water.

[0027] Without being bound by theory, it is suggested that in coated compositions according to embodiments of the invention, the liquid fatty acid reacts with the calcium silicate present in the cement to form insoluble carboxylate salts of the calcium silicate and forms a hard hydrophobic coating surrounding the active agent. The hard hydrophobic opaque coating layer, when in an aqueous environment, limits the flow of water in and out of the coated active agent, thereby limiting the release of water-soluble active from the composition.

[0028] Other uses of the hard hydrophobic coating described herein include coating of active agents to prevent their reaction with other active agents. For example, in case of the active agent urea, a hard hydrophobic coating may be applied, and a mixture may then be formed with coated urea and other fertilizers such as single superphosphate (SSP) or triple superphosphate (TSP), thereby allowing the fertilized to be blended and stored together without forming a chemical reaction between the urea and the SSP or TSP. In such cases, the coating layer may be as low as about 5% of the weight of the composition, as the coating does not necessarily need to provide sustained release properties. It should be noted that fine particles, such as powders of active agent, including micronutrients can be coated using the same methods while the coating agent (i.e Portland Cement + Fatty Acid) serves also as a binder in order to form a granular product.

[0029] Optionally, the active agent is selected from the group consisting of: a fertilizer, a pesticide, a nutritional agent, and a seed. Optionally, the fertilizer is a nitrogen-containing fertilizer such as urea. The fertilizer may be an NPK fertilizer. Optionally, the nutritional agent is selected form the group consisting of NPN and an amino acid. Other fertilizers which may be used include but are not limited to potassium nitrate, potassium sulfate, potassium chloride, monoammonium phosphate, diammonium phosphate and calcium ammonium nitrate.

[0030] According to an embodiment, the composition is in granular form, optionally having a particle diameter of between 0.1 -5 mm. optionally, in the range of 0.5-4 mm, or 1-4 mm, optionally for 90% by weight or more of the composition.

[0031] According to an embodiment, the Portland cement used in the coated compositions described herein is white Portland cement. According to an embodiment, the Portland cement used in the coated compositions described herein is grey Portland cement. Optionally, a mixture of white Portland cement and grey Portland cement may be used. Optionally, the cement is selected from the group consisting of: CEM type I, 52.5 R (White and Grey), CEM type I, 52.5 N, and CEM type II, 42.5 AL. Portland cement preferably contains more than 60% of CaO and more than 15% of SiOi.

[0032] The fatty acid used to form the coating of the compositions described herein, according to some embodiments, are preferably liquid at room temperature, before reaction with Portland cement. These fatty acids may be C10-C20 fatty acid. The fatty acid may be a saturated or unsaturated fatty acid, optionally an unsaturated fatty acid. Mixtures of various types of fatty acids may be used. According to an embodiment, the unsaturated fatty acid is oleic acid. Optionally, the fatty acid used for the coating is in the form of a mixture, in form of a liquid composition comprising a fatty acid, or multiple types of fatty acid. Preferably, the liquidcomposition comprises at least 50% fatty acid, preferably at least 70% fatty acid. Optionally the liquid composition comprising fatty acid is tall oil, or tall oil fatty acid.

[0033] According to an embodiment, the coated agricultural composition comprises a hard hydrophobic coating surrounding the active agent, in an amount of between 5% by weight and 50% by weight of the coated agricultural composition, optionally, between 10% and 30% by weight of the coated agricultural composition. Optionally, the amount of coating, by weight, is less than 20% of the coated agricultural composition.

[0034] It has been found by the inventor that the quality of Portland cement may vary. Due to these variations, the reaction between the Portland cement and the Fatty acid may produce microcracks in the coating layers. To prevent microcracking in the hydrophobic coating which may impact the release profile of the active agent, an additive may be added to the fatty acid. Optionally, the additive is selected from the group consisting of a biodegradable wax and a biodegradable polymer. Optionally, the additive is a biodegradable wax, optionally in an amount of between 2% and 20% of the fatty acid composition, optionally 5% to 10% of the fatty acid composition. Optionally, the additive is a biodegradable polymer, optionally in an amount between 0.5% to 10% of the fatty acid composition, optionally 1% to 3% of the fatty acid composition.

[0035] According to an embodiment, the percentage, by weight, of fatty acid in the coating layer is 15%-50%, optionally 30%-40%.

[0036] According to an embodiment, the coating layer has less than 1% water, less than 0.5% water, or most preferably, the coating layer is free of water. Preferably, the coating layer comprises a reaction product of a fatty acid and Portland cement. Preferably, this reaction occurs in the absence of water, or in an environment of less than 1% water, preferably less than 0.5% water. It is preferable to prepare compositions described herein the absence of water, as contact between water and Portland cement will create concrete, which may interfere with the slow- release profile associated with coatings based on Portland cement / fatty acid. Preferably, the compositions are prepared with dry ingredients which are substantially free of water, having less than 1%, preferably less than 0.5% water.

[0037] According to an embodiment, the coating layer comprises, in addition to Portland cement and a fatty acid, a mineral filler. The mineral filler is optionally a metal oxide, optionally CaO or MgO. Optionally, the mineral filler is selected from the group consisting of CaO, MgO, CaCOs. a kaolin, and clay. Optionally, the mineral filler is CaO and / or MgO. The ratio of Portland cement to mineral filler may be between 1: 10 and 10: 1. Optionally, the ratio of Portland cement to mineral filler is between 1:3 and 3: 1.

[0038] According to an embodiment, described is a coated agricultural composition, consisting essentially of: an active agent; and a hard hydrophobic coating surrounding the active agent, the coating consisting essentially of Portland cement and a fatty acid, optionally further consisting essentially of a mineral filler.

[0039] According to some embodiments, coated agricultural compositions may comprise an outer coating, external to the first coating formed by combination of Portland cement and fatty acid. The outer coating optionally comprises a vegetable oil. Coated agricultural compositions having such outer coatings have been shown to improve slow release profiles, have better mechanical resistance to impact and attrition relative to comparable compositions having only a hard hydrophobic coating surrounding the active agent without an outer coating. Optionally, the outer coating layer consists essentially of a vegetable oil. Optionally, the vegetable oil used in the outer coating layer is selected from the group consisting of soybean oil, canola oil, sunflower oil, corn oil, and linseed oil.

[0040] According to an embodiment in which an outer coating is present, the percentage, by weight, of the outer coating, is between 0.2% to 5%, preferably between 0.5% and 2.5% of the coated agricultural composition.

[0041] According to an embodiment, described herein are methods for coating active agents comprising: obtaining an active agent; and contacting the active agent with Portland cement and a fatty acid. Optionally, the active agent is in the form of a granule, which is contacted by a liquid fatty acid composition, wherein the fatty acid is a free fatty acid. Optionally, the fatty acid is heated and combined with an additive, selected from the group consisting of a biodegradable wax and a biodegradable polymer to form. Optionally, the fatty acid composition comprising a fatty acid and an additive is combined then cooled to about 30°C before contacting the active agent. After contacting the granule with the liquid fatty acid composition, Portland cement, optionally in combination with a mineral filler, is added. Upon addition, Portland cement and fatty acid react and begin to harden. Upon hardening and formation of a first layer, additional liquid fatty acid and Portland cement may be added to the coated active agent to form a second layer. This process may be repeated, optionally, between 2-6 times for each batch of coated active agents. Optionally, granules are coated with a coating using a rotating apparatus such as a rotating drum apparatus.

[0042] The methods described herein may be performed with active agent, Portland cement, fatty acid composition and optionally additive and / or mineral filler, using types described above, and in ratios as described above.

[0043] The methods described herein may be performed at room temperature. No heating is required to perform these methods, therefore only small amounts of energy may be used in preparing such compositions. The method described herein does not produce effluents and / or other by products which negatively impact the environment.

[0044] Compositions described herein, whether they comprise an oil-based outer coating or not, may further comprise an additional biodegradable organic based coating, for example a coating formed from a polysaccharide, optionally selected from the group consisting of a starch and a cellulose. Additional biodegradable polymers may also be used.

[0045] Further described herein are compositions as described above, for use in assisting the growth of a plant or an animal.

[0046] Further described herein, according to an embodiment, is a coated agricultural composition comprising: an active agent; and a hard, hydrophobic coating surrounding the active agent, the coating comprising Portland cement and a fatty acid, wherein the fatty acid in the coating is between 15% -45% of the coating by weight. Optionally, the active agent is selected from the group consisting of: a fertilizer, a pesticide, a nutritional agent, and a seed, preferably a fertilizer. Optionally, the fertilizer is a nitrogen containing fertilizer. Optionally, the fertilizer is urea or NPK. Optionally, the active agent is a nutritional agent. Optionally, the nutritional agent is non-protein nitrogen. Optionally, the active agent is a granule having a diameter of between 0.5-4 mm. Optionally, the Portland cement comprises more than 55% CaO and more than 15% SiO2. Optionally, the fatty acid is a C10-C20 fatty acid, optionally, oleic acid, optionally tall oil or tall oil fatty acid. Optionally, the composition comprises hard hydrophobic coating in an amount of between 5% and 50% by weight of the coated composition. Optionally, the composition comprises hard hydrophobic coating in an amount of between 5% to 40% by weight of the coated composition. Optionally, the fatty acid in the coating is between 20%-40% of the coating by weight. Optionally, the coating layer further comprises a mineral filler. Optionally, mineral filler is selected from the group consisting of CaO and MgO. Optionally, the ratio of Portland cement to mineral filler is between 1: 10 and 10: 1. Optionally, the hard, hydrophobic coating further comprises an additive. Optionally, the additive is selected from the group consisting of: a water-insoluble, biodegradable polymer, and a biodegradable wax. Optionally, the additive comprises a biodegradable wax, added in an amount of between 2-20% of the weight of the fatty acid. Optionally, the additive comprises a water-insoluble, biodegradable polymer, added in amount of between 0.5 and 10% of the weight of the fatty acid. Optionally, the coating comprises less than 1% by weight of water. Optionally, the coating comprises less than 0.5% water. Optionally, the coating is free of water. Optionally, thecomposition further comprises an outer coating external to the hard, hydrophobic coating, wherein the outer coating comprises a vegetable oil. Optionally, the vegetable oil is selected from the group consisting of: soybean oil, canola oil, corn oil, sunflower oil and linseed oil. Optionally, the weight of the outer coating is between 0.2% and 5% by weight of the composition. Optionally, the composition is free of plastic. Optionally, the composition is for use in agriculture, optionally for use in enhancing growth of a crop. Optionally, upon contact with water maintained at 25 °C ±2 °C, at a ratio by weight of 1 part coated active agent to 10 parts water, the composition loses less than 50% of its weight over the first 24 hours. Optionally, upon contact with water maintained at 25 °C ±2 °C, at a ratio by weight of 1 part coated active agent to 10 parts water, the composition loses less than 15% of its weight over the first 24 hours. Optionally, the composition is for use in enhancing growth of an animal.

[0047] Further described herein, according to an embodiment, is method for coating an active agent with a hard hydrophobic coating, comprising, a. contacting the active agent with a combination of Portland cement and a liquid fatty acid composition to form a coating, and b. allowing the coating to harden, thereby forming a hard, hydrophobic coating. Optionally, the active agent is selected from the group consisting of: a fertilizer, a micronutrient, a pesticide, a nutritional agent, and a seed. Optionally, the active agent is a granule having a diameter of between 0.5-4 mm. Optionally, the method further comprises adding a mineral filler to the Portland cement. Optionally, the active agent is added in an amount of between 9.5: 0.5 and 6:4 relative to the weight of the Portland cement, liquid fatty acid composition, and mineral filler. Optionally, the ratio of fatty acid to Optionally, contacting is performed in a rotating apparatus. Optionally, after hardening of the coating, a further layer of coating is formed by repeating steps a. and b., optionally 2-6 times. Optionally, method is performed in the absence of water. Optionally, the method further comprises contacting the external surface of the hard hydrophobic coating with a vegetable oil, and allowing the vegetable oil to solidify. Optionally, the vegetable oil is selected from the group consisting of soybean oil, canola oil, com oil, sunflower oil and linseed oil. Optionally, the coating hardens within 15 minutes from the contacting of step a. Optionally, steps a and b are performed at room temperature. Optionally, the liquid fatty acid composition further comprises an additive, selected from the group consisting of: a water- insoluble, biodegradable polymer, and a biodegradable wax.

[0048] The following examples are provided to illustrate certain particular features and / or embodiments. These examples should not be construed to limit the disclosure to the features or embodiments described.EXAMPLES

[0049] Example 1: Evaluation of reactions between oils and fatty acid compositions and Portland Cement

[0050] To determine if various oils and fatty acid-containing compositions (liquid reagents) could harden upon contact with Portland cement, liquid reagents were combined, in a ratio of 10 g of Portland cement to 2 g of liquid reagent, at a temperature of 25 °C, and their hardening time was measured, and is presented below in Table 1. Oleic acid (C 18: 1-79.8%; C18:2-12.3%) was obtained from Chen Samuel Chemicals Ltd. Tall oil fatty acid and tall oil were both obtained from Ingevity (North Charleston, SC, USA). Tall oil (Altavag 3030) comprises 75% fatty acid and 25% rosin acid. Tall oil fatty acid (Altapyne L-5-A) comprises 93% fatty acid. White Portland Cement is type CEM I, 52.5 R, produced by Oyak, Cimento, Turkey. Gray Portland Cement 1 is CEM 152.5 N, produced by Medcem, Turkey. Gray Portland Cement 2 is CEM I, 52.5 R, and produced by Nesher Cement, Israel. Gray Portland Cement 3 is CEM II 42.5 R AL, and produced by Nesher Cement, Israel. CaO powder was provided by Chen Samuel Chemicals, and comprised 98% CaO. Soybean oil, canola oil, com seed oil, sunflower oil, linseed oil, and olive oil were all commercially available food-grade oils. Portland cement and CaO were used in their dry form.

[0051] Table 1:

[0052] As seen in table 1, when various types of Portland cement was combined with compositions comprising free fatty acids in amounts of 75% and above, including oleic acid, tall oil and tall oil fatty acid, the cement solidified either rapidly, or within a few minutes through an exothermic reaction to form a hard, hydrophobic coating, indicating that they would be feasible for use for biodegradable coatings of active agents. As soybean, canola, other vegetable oils, and olive oil contain primarily triacylglycerols, these liquid reagents when combined with Portland cement and / or CaO formed a viscous paste and did not solidify, even after a month, and therefore are not acceptable for preparing primary coatings of active agents through mixing with Portland cement or CaO.

[0053] Example 2A: Manufacture of coated active agent

[0054] Coated active agents comprising fertilizer were prepared using the following general method: active agent granules, at a weight of 60 g, were introduced into a rotating drum having a diameter of 15 cm and were rotated at a speed of between 30-100 revolutions per minute. Liquid fatty acid-containing composition was sprayed via a pipet nozzle over thefertilizer surface while rotating, over the course of a few minutes. After coating, a measured amount of Portland cement powder, optionally comprising a filler, was added to the rotating drum. After a first layer was completed and dried, subsequent layers were added by returning to the step of spraying liquid fatty acid-containing composition, then further addition of Portland cement powder, optionally comprising a filler. The coating process is performed at ambient conditions.

[0055] When an additive such as a biodegradable polymer or biodegradable wax was added to the fatty acid-containing composition, the fatty acid was heated to a temperature of up to 90°C, the additive was added, and the composition was cooled to a temperature of about 30°C. The fatty acid composition remained in liquid form at a temperature of about 30°C, and was then applied as above.

[0056] Example 2B: Analysis or release profile of coated active agents

[0057] Coated active agents were placed in a plastic container filled with tap water maintained at 25°C ±2°C, at a ratio by weight of 1 part coated active agent to 10 parts water. Analyses were performed at various time intervals between 1 day and 60 days. Each 5 days, about 50% of the water in each container was replaced by fresh tap water. At the end of the designated time, the Fertilizer was filtered out of the water and placed in a drying oven at 80°C for 8 hours until fully completion of drying, and weighed, and compared to the starting weight. As the coating is practically water insoluble, and the active agents used in the experiments are highly soluble, it is assumed that the weight loss is attributable to the release of the active agent only.

[0058] Example 3 A: Manufacture of coated fertilizer, and analysis of release profile

[0059] The procedure of Example 2A was followed to coat urea active agent with whitePortland cement type CEM I, 52.5 R. The urea used was produced by Chen Samuel Chemicals Ltd. (Kiryat Ata, Israel) and was in the form of granules, having a diameter of 1-4 mm, and 60 g of urea were used in the example. Each coating layer contained 1 g of oleic acid and 1.6 g of white cement. After each coating and self-drying, the sample was weighed, and the number of coatings, weight, coating weight and percentage urea by weight is listed in table 2 below.

[0060] Table 2:

[0061] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 60 days. The results of percent weight loss are shown in table 3 below.

[0062] Table 3:

[0063] As shown in Table 3, increase in number of coating layers decreases the release of the urea from the coated composition. In samples 3, 4, and 5, an acceptable release profile was shown, as less than 15% of the urea was released in the first day, and the composition continues to release urea over 30 days. This release rate was attained using a coated composition comprising about 10-16% coating by weight. The ratio of fatty acid to cement was about 1: 1.6 by weight in the coating.

[0064] Example 3B: Manufacture of coated fertilizer, and analysis of release profile

[0065] The procedure of Example 2A was followed to coat urea with gray Portland cement 1. Each coating layer contained 1 g of oleic acid and 2.2 g of Portland cement. After each coating and drying, the sample was weighed, and the number of coatings, weight, coating weight and percentage urea by weight is listed in table 4.

[0066] Table 4:

[0067] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 60 days. The results of percent weight loss are shown in table 5 below.

[0068] Table 5:

[0069] As shown in Table 5, increase in number of coating layers decreases the release of the urea from the coated composition over time. In samples 8 and 9, an acceptable release profile was shown, as less than 15% of the urea was released in the first day, and the composition continues to release urea over 30 days. Sample 9 showed release of urea even at 60 days. This release rate was attained using a coated composition of gray Portland cement (CEM I 52,5 N) comprising about 15-20% coating by weight. The ratio of fatty acid to cement was about 1:2.2 by weight in the coating.

[0070] Example 3C: Manufacture of coated fertilizer comparing number of coatings

[0071] Two additional samples were made with white Portland cement, having similar amounts of ingredients as Sample 4 of example 3A to determine if numbers of coatings impacts release profile. Here too, 60 g of urea were used, and coating layers, as well as oleic acid and cement amounts per layer are shown in Table 6 below. The general procedure for the manufacture was performed as in Example 2A.

[0072] Table 6:

[0073] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 45 days. The results of percent weight loss are shown in table 7 below.

[0074] Table 7:

[0075] As shown in table 7, sample 4 showed a slightly more delayed release profile relative to samples 10 and 11 at 45 days, even though at days 1, 5, and 15, more release was evident in sample 4. More coatings require more coating processing time but may increase longterm (45 days and more) resistance to release.

[0076] Example 3D: Manufacture of coated fertilizer with various types of Portland cement

[0077] Additional samples were made with various types of Portland cement, and were compared with Sample 11 from Example 3C. The general procedure for the manufacture was performed as in Example 2A. Here too, 60 g of urea were used, and coating layers, as well as oleic acid and cement amounts per layer are shown in Table 8 below. Sample 11 was prepared with white Portland cement. Sample 12 was prepared with gray Portland cement 1. Sample 13 was prepared with gray Portland cement 2. Sample 14 was prepared with gray Portland cement 3. The compositions of the cement and their respective setting times (in minutes) are shown in Table 9.

[0078] Table 8:

[0079] Table 9:

[0080] Slightly more cement was used when combining Gray Portland cement 2 and 3 with oleic acid due to the slower setting time of these types of cement.

[0081] The release rates of urea were measured according to the procedure in example2B, and the results are shown in Table 10 below, at time points between 1 and 30 days.

[0082] Table 10:

[0083] All samples 11-14 showed acceptable results, however Gray Portland Cement 2 and 3 showed rapid release of urea on day 1.

[0084] Example 3E: Manufacture of coated fertilizer with various types of Portland cement and fatty acid

[0085] Additional samples were made with various types of Portland cement and fatty acid containing compositions such as tall oil fatty acid (L-5-A) and tall oil (3030). The general procedure for the manufacture was performed as in Example 2A.

[0086] For each sample, 60 g of urea were used. Coating layers, including cement type and amount, and fatty acid type and amount, are detailed in Table 11 below.

[0087] Table 11:

[0088] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 30 days. The results of percent weight loss are shown in table 12 below.

[0089] Table 12:

[0090] As seen in Table 12, oils such as tall oil fatty acid provide similar results in release profile as oleic acid, as evident from a comparison between samples 4 and 15, which had similar release profiles at 1, 15, and 30 days. These results indicate that other fatty oil compositions may be used to combine with Portland cement to prepare biodegradable coatings for controlled release active agents.

[0091] Example 4: NPK coated fertilizer

[0092] An NPK fertilizer was coated with a biodegradable coating prepared using a combination of fatty acid and Portland cement, as described in Example 2A, using NPK as an active agent, and the cement and fatty acid as in Table 13. Sample 101 represents uncoated NPK. NPK was produced by Productos Flower SA Spain, and was a 12-8-21 fertilizer having also sulfur (8%) and Magnesium (3.5). The NPK was in the form of granules, having a diameter of 0.5-4 mm.

[0093] Table 13:

[0094] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 30 days. The results of percent weight loss are shown in table 14 below.

[0095] Table 14:

[0096] As seen from Table 14 when comparing the release profile of sample 101 to samples 102-104, introduction of a biodegradable coating comprising various types of cements and fatty acids delays the release of NPK from the composition.

[0097] Example 5: Coatings of fertilizer with coatings comprising additional ingredients

[0098] Attempts were made to use mineral oxides with or without Portland cement to coat active ingredients. Portland cement was blended with CaO and / or MgO and metal oxides alone, or were used in place of Portland cement (samples 23 and 25) to prepare coatings, using the method described in example 2 A. MgO powder was provided by Grecian Magnesite, in the form of “Vitalmag 92” which had an MgO content of greater than 88.5%. CaO powder was provided by Chen Samuel Chemicals and comprised 98% CaO.

[0099] In each sample, 60 g of urea were used, and three coating layers were used to prepare the samples. Each coating layer comprised 1.6 g of Oleic acid, and solid filler (white Portland cement + metal oxide, or metal oxide alone) was used in the amounts and ratios described in table 15. Sample 11, using white Portland cement alone in combination with oleic acid was described above in example 3C.

[0100] Table 15:

[0101] Samples prepared were tested for release profile using the method of Example 2B, at time intervals between 1 and 30 days. The results of percent weight loss are shown in table 16 below.

[0102] Table 16:

[0103] Active agents comprising metal oxides MgO and CaO alone (without Portland cement) had rapid release profiles on day 1 (over 20%) and day 5 (over 50%), making these coatings less suitable for coating active agents. Combinations of Portland cement with MgO and CaO did provide suitable release rates. Such combinations may be acceptable for uses in which silicate content of cement should be decreased, such as in providing ruminant nutrition in the form of NPN.

[0104] Example 6: Dissolution of coated active agents

[0105] Samples described in example 5 were tested for dissolution, using the following procedure. A hot plate was equipped with a magnetic stirrer. A glass beaker filled with 500 ml water was placed on the hot plate. Coated urea granules weighing 10 grams were placed in a mesh basket and the mesh basket with the urea sample was inserted in the water, which wasmaintained at 39°C + / - 1°C. A magnetic stirrer rotated at about 100 RPM. Weight loss of urea samples after dissolution time of 1 and 3 hours were evaluated as described above and the weight loss in terms of percentage of weight lost at these time points is listed in Table 17.

[0106] Table 17:

[0107] The addition of CaO or MgO to Portland cement compositions expedites the speed of the coating process, as the reaction between the fatty acid and the solid mixture of metal oxide with Portland cement and subsequent solidification is faster than the reaction between fatty acid and Portland cement alone. In addition, NPN using coated urea comprising blends of Portland Cement and metal oxides such as CaO and MgO can be effective in reducing dissolution time in systems comparable to ruminants’ digestive systems, indicating that NPN can be administered in a safer, more effective way. As the combinations of Portland cement with metal oxides have lower silicate content than Portland cement alone, such combinations can be reacted with fatty acids to form coatings of NPN, and can be administered to ruminants without surpassing regulatory limits of silicate administration to the ruminants.

[0108] Example 7A: Outer coatings

[0109] The procedure of Example 2 A was followed to coat urea active agent with a modified cement (MC) grey Portland cement type CEM I, 52.5 R, in combination with CaO. The weight ratio of CaO to Portland cement in the MC was 1 to 3. 60 g of urea were used. Five coatings using Portland cement and CaO in combination with oleic acid were performed. The weight ratio of oleic acid to the total coating was 0.45. A sample designated sample 26 was prepared using this procedure, using the ingredients as detailed in Table 18.

[0110] Table 18:

[0111] After preparation of sample 26, some of sample 26 was saved for testing while a portion was coated with an outer coating by adding a vegetable oil. Outer coating was prepared by introducing a coated agricultural composition (having a primary coat consisting of MC and a fatty acid) into a rotating drum spinning at 30-100 revolutions per minute, and adding liquid vegetable oil via a pipet nozzle over the coated agricultural composition. Upon addition of the vegetable oil, the vegetable oil reacted with the first coating comprised of Portland cement and oleic acid, and solidifies over the course of a few hours. Optionally, solidification of the vegetable oil can be expedited by blowing of warm air on the composition outer surface after adding the coating while the product is still rotating in the drum. No liquid oil remained on the outer surface of the samples, and a dry, free flowing product was obtained. The amount vegetable oil used in the coating was 1.5% relative to the total weight of the agricultural product. The amount by weight of urea in the samples having an outer vegetable oil-based coating was 87.3% by weight. Sample 26 and samples having an outer coating were tested for release profile using the method described in Example 2B for 24 hours. Table 19 details the types of oils used, and weight loss for each of the samples.

[0112] Table 19:

[0113] Table 19 indicates that an outer vegetable oil-based coating is effective in inhibiting release and improving release profile of coated agricultural compositions. Samples 26 and 27 were further tested for release profile at time intervals between 1 and 45 days. The percent of weight loss is shown in Table 20:

[0114] Table 20:

[0115] Table 20 indicates that an outer coating based on a vegetable oil, can be used to enhance release profile, by limiting release in the short term (1-5 days) and also in the long term (30-45 days).

[0116] Example 7B: Additional outer coatings:

[0117] Additional samples were prepared as in Example 7A, but with the following changes. Grey Portland cement (CEM type I, 52.5 R-A product of Nesher) was used without additional CaO, and the ratio of oleic acid to total coating weight was 0.3. The product of the primary coating was designated sample 32. Sample 32 was then coated with canola oil, by adding canola oil in an amount of 1.2% of the weight of the sample 32, and after coating was designated sample 33. Their contents are detailed in table 21.

[0118] Table 21:

[0119] Example 8: Structural integrity of coated agricultural compositions

[0120] A drop test was performed using a vertical polypropylene pipe having a diameter of 4 cm and a length of 2 meters. The pipe was positioned vertically. A hopper was situated at the upper end of the pipe. Coated samples, in amounts of 100 grams each, were fed into the hopper and subjected to a fall (by gravity) of 2 meters through the pipe and were collected in a plastic vessel positioned at the bottom of the pipe after colliding with the inner surface of the collecting vessel.

[0121] Collected particles were screened over a 200# (Mesh screen) in order to measure the fine particles obtained out of the impact / attrition. Samples underwent 0, 1, or 3 drop sessions, and were measured for release profile after 24 hours as described in Example 2B. In addition, weight loss due to attrition caused as a result of impact after falling was measured. The results are shown in table 22.

[0122] Table 22:

[0123] When comparing the attrition of the compositions coated with a Portland cement / fatty acid coating alone with those coated with an outer vegetable oil coating, those coated with a vegetable oil outer coating (27, 28, and 33) underwent less attrition than those without the vegetable oil outer coating (26 and 32). In coated agricultural products which undergo packaging and shipping, reducing attrition is desirable, as a product should maintain its composition without attrition / dust formation when being transported from a manufacturing site to an end user, and outer coatings comprising vegetable oil may be used to reduce attrition.

[0124] Samples prepared with both canola and soybean oil-based outer coating were shown to have slower release than equivalent samples without the oil-based outer coating.

[0125] Without being bound by theory, it is suggested that upon application of vegetable oils to coated compositions (having a primary coating made from fatty acids and Portland cement) the oils react with oxygen present in the ambient air, and solidify to form a film resulting in polymerization of the oil, and subsequent crosslinking involving the oils and the hardened primary coating. Attempts to use vegetable oil in combination with Portland cement as a primary coating were not successful as shown in Example 1, table 1, as no hard coating was formed. Surprisingly, application of vegetable oil as an outer coating external to a hardened fatty acid / Portland cement was not only successful in forming a solidified, oil-based coating, but also enhanced slow-release qualities and reduced attrition of resulting compositions.

[0126] Example 9: Preparation of coatings including fatty acids with biodegradable polymer and / or biodegradable wax

[0127] In order to improve the release profile of coated active agent, attempts were made to add water insoluble biodegradable polymer and / or biodegradable wax to the fatty acid coatings. Soy wax was obtained from Hudong Household Auxiliaries Co., Ltd China. Ethylcellulose polymer (ETHOCEL STD 100) obtained from Dupont. Soy wax and / or ethylcellulose and Oleic acid at various weight percent were placed in a glass beaker over a hot plate at 80°C and mixed by a magnetic stirrer for 10 minutes. The mixture was then cooled to about 30°C. At this temperature the product was a stable liquid which was pumpable, throughout the duration of the coating process.

[0128] The samples of fatty acid composition were prepared using the ingredients in the amounts shown in Table 23.

[0129] Table 23:

[0130] Coated urea was then produced following the procedure in example 2A, using white Portland cement type CEM I, 52.5 R, and urea granules having a diameter of 1-4 mm. 60g of urea were used in each batch. Each coating layer contained 1 g of fatty acid composition, either with only oleic acid, or in combination with biodegradable fat / polymer additive. Three coating layers per sample were applied. After all three coating layers were applied, an additional outer coating layer of canola oil was provided, using canola oil in an amount of 1% by weight. After each coating and drying, each sample was weighed. The number and type of coating is detailed in Table 24:

[0131] Table 24:

[0132] The release rates of urea were measured according to the procedure described in Example 2B and are shown in Table 25.

[0133] Table 25:

[0134] As evident from Table 25, addition of additives such as a biodegradable wax, optionally in combination with a biodegradable water-insoluble polymer such as ethylcellulose, reduced the percentage of urea active agent dissolved within 24 hours. Samples 35-38, in which the fatty acid composition contained between 2-20% soy wax relative, showed improved lower levels of weight loss relative to the sample using fatty acid alone, without additive. Similarly, when soy wax (6% by weight) used in combination with a biodegradable water-insoluble polymer in an amount of 1-2% by weight of the fatty composition, the weight loss over 24 hours was greatly improved relative to the sample using fatty acid alone, without additive. Without being bound by theory, it is suggested that introduction of additives may prevent the effect of microcracking in the hard coating layer, thereby improving / lowering weight loss of coated active agents.

[0135] In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.

Claims

CLAIMS1. A coated agricultural composition comprising: an active agent; and a hard, hydrophobic coating surrounding the active agent, the coating comprising Portland cement and a fatty acid, wherein the fatty acid in the coating is between 15%-45% of the coating by weight.

2. The composition according to claim 1 wherein the active agent is selected from the group consisting of: a fertilizer, a pesticide, a nutritional agent, and a seed.

3. The composition according to claim 2 wherein the active agent is a fertilizer.

4. The composition according to claim 3 wherein the fertilizer is a nitrogen containing fertilizer.

5. The composition according to claim 4 wherein the fertilizer is urea or NPK.

6. The composition according to claim 1 wherein the active agent is a nutritional agent.

7. The composition according to claim 6 wherein the nutritional agent is non-protein nitrogen.

8. The composition according to any one of the previous claims wherein the active agent is a granule having a diameter of between 0.5-4 mm.

9. The composition according to any one of the previous claims wherein the Portland cement comprises more than 55% CaO and more than 15% SiCL.

10. The composition according to any one of the previous claims wherein the fatty acid is a C10-C20 fatty acid.

11. The composition according to claim 10 wherein the fatty acid is oleic acid.

12. The composition according to claim 1 wherein the fatty acid is tall oil or tall oil fatty acid.

13. The composition according to any one of the previous claims wherein the composition comprises hard hydrophobic coating in an amount of between 5% and 50% by weight of the coated composition.

14. The composition according to claim 13 wherein the composition comprises hard hydrophobic coating in an amount of between 5% to 40% by weight of the coated composition.

15. The composition according to any one of the previous claims wherein the fatty acid in the coating is between 20%-40% of the coating by weight.

16. The composition according to any one of the previous claims wherein the coating layer further comprises a mineral filler.

17. The composition according to claim 16 wherein the mineral filler is selected from the group consisting of CaO and MgO.

18. The composition according to any one of claims 16-17 wherein the ratio of Portland cement to mineral filler is between 1: 10 and 10: 1.

19. The composition according to any one of the previous claims wherein the hard, hydrophobic coating further comprises an additive.

20. The composition according to claim 19 wherein the additive is selected from the group consisting of: a water- insoluble, biodegradable polymer, and a biodegradable wax.

21. The composition according to claim 20 wherein the additive comprises a biodegradable wax, added in an amount of between 2-20% of the weight of the fatty acid.

22. The composition according to claim 20 wherein the additive comprises a water-insoluble, biodegradable polymer, added in amount of between 0.5 and 10% of the weight of the fatty acid.

23. The composition according to any one of the previous claims wherein the coating comprises less than 1% by weight of water.

24. The composition according to claim 23, wherein the coating comprises less than 0.5% water.

25. The composition according to claim 24, wherein the coating is free of water.

26. The composition according to any one of the previous claims, further comprising an outer coating external to the hard, hydrophobic coating, wherein the outer coating comprises a vegetable oil.

27. The composition according to claim 26, wherein the vegetable oil is selected from the group consisting of: soybean oil, canola oil, com oil, sunflower oil and linseed oil.

28. The composition according to any one of claims 25-27 wherein the weight of the outer coating is between 0.2% and 5% by weight of the composition.

29. A method for coating an active agent with a hard hydrophobic coating, comprising, a. contacting the active agent with a combination of Portland cement and a liquid fatty acid composition to form a coating, and b. allowing the coating to harden, thereby forming a hard, hydrophobic coating.

30. The method according to claim 29 wherein the active agent is selected from the group consisting of: a fertilizer, a micronutrient, a pesticide, a nutritional agent, and a seed.

31. The method according to claim 29 or 30 wherein the active agent is a granule having a diameter of between 0.5-4 mm.

32. The method according to any one of claims 29-31 further comprising adding a mineral filler to the Portland cement.

33. The method according to any one of claims 29-32 wherein the active agent is added in an amount of between 9.5: 0.5 and 6:4 relative to the weight of the Portland cement, liquid fatty acid composition, and mineral filler.

34. The method according to any one of claims 29-33 wherein the ratio of fatty acid to Portland cement and mineral filler is between 3:17 and 9: 11.

35. The method according to any one of claims 29-34, wherein contacting is performed in a rotating apparatus.

36. The method according to any one of claims 29-35 wherein after hardening of the coating, a further layer of coating is formed by repeating steps a. and b.

37. The method according to claim 36 wherein steps a. and b. are repeated 2-6 times.

38. The method according to any one of claims 29-37 wherein the method is performed in the absence of water.

39. The method according to any one of claims 29-38, further comprising contacting the external surface of the hard hydrophobic coating with a vegetable oil, and allowing the vegetable oil to solidify.

40. The method according to claim 39 wherein the vegetable oil is selected from the group consisting of soybean oil, canola oil, corn oil, sunflower oil and linseed oil.

41. The method according to any one of claims 29-40 wherein the coating hardens within 15 minutes from the contacting of step a.

42. The method according to any one of claims 29-41 wherein steps a and b are performed at room temperature.

43. The method according to any one of claims 29-42 wherein the liquid fatty acid composition further comprises an additive, selected from the group consisting of: a water-insoluble, biodegradable polymer, and a biodegradable wax.

44. A composition according to any one of claims 1-28 and free of plastic.

45. A composition according to any one of claims 1-28 for use in agriculture.

46. The composition according to any one of claims 1-5 or 8-28 for use in enhancing growth of a crop.

47. The composition according to claim 46, wherein upon contact with water maintained at 25°C ±2°C, at a ratio by weight of 1 part coated active agent to 10 parts water, the composition loses less than 50% of its weight over the first 24 hours.

48. The composition according to any one of claims 44-47 wherein upon contact with water maintained at 25°C ±2°C, at a ratio by weight of 1 part coated active agent to 10 parts water, the composition loses less than 15% of its weight over the first 24 hours.

49. The composition according to any one of claims 1 or 6-28 for use in enhancing growth of an animal.

50. A product manufactured according to the method of any one of claims 29-39.

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