Urea-containing liquid fertilizer, manufacturing method thereof, and method for inhibiting growth of urea acicular crystal

Abstract

To provide a liquid fertilizer, in a urea-containing liquid fertilizer, where growth of a urea acicular crystal is inhibited, a manufacturing method thereof, and a method for inhibiting the growth of the urea acicular crystal.SOLUTION: A urea-containing liquid fertilizer contains urea, a compound A, and water, where the compound A is an organic compound that has a straight-chain structure of 6C or greater, has one or more functional groups among one or more kinds selected from the group consisting of a hydroxy group, a carbonyl group, an amino group, and an amide group, and has solubility where 0.01 g or more thereof dissolves in 100 g of water under 1 atmospheric pressure at 20°C.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a urea-containing liquid fertilizer, and more particularly to a urea-containing liquid fertilizer in which the growth of urea needle crystals is inhibited, a method for producing the same, and a method for inhibiting the growth of urea needle crystals in a urea-containing liquid fertilizer. [Background technology]

[0002] In recent years, mechanical fertilization has become widespread to address the need for a reduction in agricultural labor and production costs. Furthermore, liquid fertilizers that can be used even in rainy weather have become popular for side-dressing.

[0003] For example, Patent Document 1 describes a method for producing a paste fertilizer by wet-pulverizing both fertilizer salts and a suspension stabilizer, characterized in that the wet-pulverization is carried out mainly by shearing and / or friction, and by this action, the solid particles dispersed in the liquid have an average particle size of 30 to 100 μm.

[0004] In Patent Document 2, water-soluble polyphosphoric acid and / or its salt is used as a P 2 O 5 The paper describes a paste fertilizer that is free from crystal precipitation or two-layer separation over a long period of time over a wide temperature range, is easy to handle, and can be easily applied mechanically, and is characterized by containing 1 to 10% by weight of water-soluble polymer as a fertilizer and 0.05 to 1.5% by weight of at least one water-soluble polymer selected from guar gum, xanthan gum, and polyacrylamide.

[0005] Patent Document 3 describes a method for preventing crystal growth in liquid fertilizer, which is characterized by adding potassium humate and / or a polycarboxylic acid type polymeric surfactant to the liquid fertilizer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-206567 [Patent Document 2] Japanese Patent Application Publication No. 9-40485 [Patent Document 3] Japanese Patent Application Publication No. 9-48687 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to further reduce labor and transportation costs, there is a demand for higher concentrations of nitrogen and other components. Furthermore, liquid fertilizers are being reevaluated due to the microplastics issue. Urea is often used to make highly concentrated liquid fertilizers. This is because urea has a nitrogen content of 46%, which is higher than other nitrogen sources and makes it an excellent nitrogen source, as well as being highly soluble in water and inexpensive.

[0008] However, the solubility of urea changes greatly depending on temperature, and coarse needle-like crystals easily precipitate and grow during storage, which can cause nozzles to become clogged during mechanical fertilization.

[0009] Therefore, an object of the present invention is to provide a urea-containing liquid fertilizer in which the growth of urea needle crystals is suppressed, a method for producing the same, and a method for suppressing the growth of urea needle crystals. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above problems, the present inventors discovered that when a water-soluble organic compound having a linear chain structure with six or more carbon atoms and having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group and an amide group is added to a urea-containing liquid fertilizer, the growth of needle-like crystals of urea is inhibited, and thus the present invention has been completed.

[0011] That is, the present invention includes the following. (1) A urea-containing liquid fertilizer comprising urea, compound A, and water, in which compound A is an organic compound having a linear structure with 6 or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more per 100 g of water at 1 atmospheric pressure and 20° C. (2) The urea-containing liquid fertilizer according to (1), in which compound A is one or more selected from the group consisting of polyethers, polycarboxylic acids, polyvinyl alcohols, polyamines, and polyamides. (3) The urea-containing liquid fertilizer according to (1) or (2), wherein compound A is one or more selected from the group consisting of polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene sorbitan trioleate, polyacrylic acid, polyvinyl alcohol, hexamethylenediamine, and polyamide. (4) The urea-containing liquid fertilizer according to any one of (1) to (3), wherein the urea content is 50% by weight or more based on the weight of water. (5) The urea-containing liquid fertilizer according to any one of (1) to (4), wherein the content of compound A is 0.01% by weight to 100% by weight based on the weight of urea. (6) The urea-containing liquid fertilizer according to any one of (1) to (5), further comprising one or more other components selected from the group consisting of fertilizer components other than urea, viscosity regulators, phase separation inhibitors, chemical slow-release fertilizers, additional elements, carboxylic acids, chelating agents, nitrification inhibitors, pesticides, and preservatives. (7) The urea-containing liquid fertilizer according to (6), wherein the viscosity adjuster and the phase separation inhibitor are one or more selected from the group consisting of carboxymethyl cellulose, guar gum, sodium alginate, xanthan gum, polyacrylamide, water-soluble polymers, inorganic additives, and polycarboxylic acid-type polymer surfactants. (8) The urea-containing liquid fertilizer according to (6) or (7), wherein the chemical slow-release fertilizer is one or more selected from the group consisting of ureaform, acetaldehyde condensed urea, isobutyraldehyde condensed urea, oxamide, guanylurea, and glyoxal urea. (9) The urea-containing liquid fertilizer according to any one of (6) to (8), wherein the total content of the other components is 1 to 50% by weight, based on the total weight of the urea-containing liquid fertilizer. (10) The urea-containing liquid fertilizer according to any one of (1) to (9), in which urea is present in a crystalline form, the average long diameter of the crystals is 2 mm or less, and the average aspect ratio of the crystals is 1 to 20. (11) The urea-containing liquid fertilizer according to any one of (1) to (10), which is used for mechanical fertilization. (12) A method for producing a urea-containing liquid fertilizer comprising urea, compound A, and water, the method comprising the step of mixing urea with compound A in water, wherein compound A is an organic compound having a linear structure having 6 or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmospheric pressure and 20°C. (13) The method according to (12), wherein compound A is at least one selected from the group consisting of polyethers, polycarboxylic acids, polyvinyl alcohols, polyamines, and polyamides. (14) The method according to (12) or (13), wherein compound A is at least one selected from the group consisting of polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene sorbitan trioleate, polyacrylic acid, polyvinyl alcohol, hexamethylenediamine, and polyamide. (15) The method according to any one of (12) to (14), wherein the content of urea is 50% by weight or more based on the weight of water. (16) The method according to any one of (12) to (15), wherein the content of compound A is 0.01% by weight to 100% by weight based on the weight of urea. (17) The method according to any one of (12) to (16), further comprising the step of adding one or more other components selected from the group consisting of fertilizer components other than urea, viscosity regulators, phase separation inhibitors, chemical slow-release fertilizers, additional elements, carboxylic acids, chelating agents, nitrification inhibitors, pesticides, and preservatives. (18) The method according to (17), wherein the viscosity modifier and the phase separation inhibitor are one or more selected from the group consisting of carboxymethylcellulose, guar gum, sodium alginate, xanthan gum, polyacrylamide, water-soluble polymers, inorganic additives, and polycarboxylic acid type polymer surfactants. (19) The method according to (17) or (18), wherein the chemical slow-release fertilizer is one or more selected from the group consisting of ureaform, acetaldehyde condensed urea, isobutyraldehyde condensed urea, oxamide, guanylurea, and glyoxal urea. (20) The method according to any one of (17) to (19), wherein the total content of the other components is 1 to 50% by weight based on the total weight of the urea-containing liquid fertilizer. (21) The method according to any one of (12) to (20), in which, by mixing with the compound A, urea in crystalline form precipitates in the obtained urea-containing liquid fertilizer, the average long diameter of the crystals is 2 mm or less, and the average aspect ratio of the crystals is 1 to 20. (22) The method according to any one of (12) to (21), wherein the intended use is mechanical fertilization. (23) A method for suppressing the growth of needle-like crystals of urea in a urea-containing liquid fertilizer, comprising the step of mixing the urea-containing liquid fertilizer with a compound A, wherein the compound A is an organic compound having a linear structure having 6 or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmospheric pressure and 20° C. (24) The method according to (23), wherein compound A is at least one selected from the group consisting of polyethers, polycarboxylic acids, polyvinyl alcohols, polyamines, and polyamides. (25) The method according to (23) or (24), wherein compound A is at least one selected from the group consisting of polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene sorbitan trioleate, polyacrylic acid, polyvinyl alcohol, hexamethylenediamine, and polyamide. (26) The method according to any one of (23) to (25), wherein the content of compound A in the urea-containing liquid fertilizer is 0.01% by weight to 100% by weight based on the weight of urea. (27) The method according to any one of (23) to (26), in which, by mixing with the compound A, urea in crystalline form precipitates in the urea-containing liquid fertilizer, the average long axis of the crystals becomes 2 mm or less, and the average aspect ratio of the crystals becomes 1 to 20. (28) The method according to any one of (23) to (27), wherein the application is mechanical fertilization. Effect of the Invention

[0012] The present invention provides a liquid fertilizer containing urea in which the growth of urea needle crystals is inhibited, a method for producing the same, and a method for inhibiting the growth of urea needle crystals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and can be embodied in various forms including modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention.

[0014] The present invention relates to a urea-containing liquid fertilizer comprising urea, compound A, and water, in which compound A is an organic compound having a linear structure with 6 or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmospheric pressure and 20°C.

[0015] Here, in the present invention, liquid fertilizer refers to liquid fertilizer, suspension fertilizer, or paste fertilizer. Liquid fertilizer is a fertilizer in which fertilizer components are completely dissolved in a liquid medium, such as water, and are in a liquid state. Liquid fertilizer is sometimes used after diluting with a further medium, such as water. Suspension fertilizer is a fertilizer in which fertilizer components are dispersed in a liquid medium, such as water, and are in a suspended state. Paste fertilizer is a high-viscosity liquid fertilizer in which fertilizer components are dispersed in the liquid fertilizer.

[0016] As a component contained in the urea-containing liquid fertilizer of the present invention, urea is a fertilizer component and has the following chemical formula: [ka] It is a compound having the formula:

[0017] Nitrogen is one of the major essential elements for plants and is used for protein synthesis, etc. Therefore, it is necessary to apply a large amount of nitrogen for plant cultivation. In addition, by increasing the concentration of nitrogen components in liquid fertilizers, the target amount of nitrogen components can be applied with a small amount, which leads to labor saving in fertilization and reduction in transportation costs. In the present invention, by using urea as the nitrogen component of the liquid fertilizer, it is possible to increase the concentration of the nitrogen components, since urea is the substance with the highest nitrogen content, with 46% of its own weight being nitrogen.

[0018] The content of urea is usually 50% by weight or more, preferably 70% by weight or more, based on the weight of the water solvent. The upper limit of the content of urea is not limited as long as the urea-containing liquid fertilizer is liquid, but is usually 200% by weight or less, preferably 180% by weight or less, based on the weight of the water.

[0019] In the present invention, compound A is an organic compound having a linear structure with 6 or more carbon atoms, having at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmosphere and 20° C. Compound A preferably has a solubility of 0.05 g or more in 100 g of water at 1 atmosphere and 20° C. In addition, the linear structure means a structure in which all carbon atoms constituting the main chain are primary carbon or secondary carbon and are connected in a straight line, and in the case of a polymer, for example, it means that there is no branch or ring in the bonding pattern between the repeating units (monomers). Examples of compound A include at least one selected from the group consisting of polyethers, polycarboxylic acids, polyvinyl alcohols, polyamines, and polyamides. Specific examples of the compound A include polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene sorbitan trioleate, polyacrylic acid, polyvinyl alcohol, hexamethylenediamine, and polyamide, and mixtures of two or more of these. As the compound A, polyethylene glycol and / or polyvinyl alcohol are preferred. The molecular weight of these compounds A is not limited, but is, for example, usually 200 to 100,000, preferably 300 to 90,000, more preferably 300 to 80,000, and particularly 400 to 80,000, as a number average molecular weight. In these compounds A, for example, the saponification degree is usually 70 mol% or more and less than 100 mol%, preferably 71 mol% to 99 mol%, and the average polymerization degree is, for example, usually 300 to 2000, preferably 500 to 1800.

[0020] For example, compound A is a polyether, such as polyethylene glycol, having a number average molecular weight of usually 200 to 30,000, preferably 300 to 30,000. For example, compound A is a polyvinyl alcohol, such as polyvinyl alcohol, having a degree of saponification usually of 70 mol% or more and less than 100 mol%, preferably 71 mol% to 99 mol%, and an average degree of polymerization usually of 300 to 2000, preferably 500 to 1800.

[0021] In the urea-containing liquid fertilizer of the present invention, if the above-described compound A is present in the liquid fertilizer, the growth of needle-like crystals of urea in the liquid fertilizer is suppressed. Therefore, the content of compound A is not limited, but is usually 100% by weight or less, preferably 0.01% by weight to 100% by weight, more preferably 0.05% by weight to 100% by weight, even more preferably 0.05% by weight to 50% by weight, and particularly 0.05% by weight to 25% by weight, based on the weight of urea. Alternatively, the weight ratio of urea to compound A (urea / compound A) is not limited, but is usually 1 or more, preferably 1 to 10,000, more preferably 1 to 2,000, even more preferably 2 to 2,000, and particularly 4 to 2,000.

[0022] For example, when compound A is a polyether, the content of the polyether is not limited, but is usually 0.01% by weight to 100% by weight, preferably 0.05% by weight to 50% by weight, based on the weight of urea. For example, when compound A is a polyethylene glycol having a number average molecular weight of usually 200 to 500, preferably 360 to 400, the content of the polyethylene glycol is not limited, but is usually 10% by weight to 100% by weight, preferably 30% by weight to 60% by weight, based on the weight of urea. For example, when compound A is a polyethylene glycol having a number average molecular weight of usually 2000 to 4000, preferably 2700 to 3300, the content of the polyethylene glycol is not limited, but is usually 5% by weight to 100% by weight, preferably 10% by weight to 60% by weight, based on the weight of urea. For example, when compound A is a polyethylene glycol having a number average molecular weight of usually 5000 to 10000, preferably 7300 to 9300, the content of the polyethylene glycol is not limited, but is usually 0.5% by weight to 100% by weight, preferably 5% by weight to 60% by weight, based on the weight of urea. For example, when compound A is a polyethylene glycol having a number average molecular weight of usually 10000 to 30000, preferably 15000 to 25000, the content of the polyethylene glycol is not limited, but is usually 0.1% by weight to 100% by weight, preferably 0.5% by weight to 60% by weight, based on the weight of urea. For example, when compound A is a polyvinyl alcohol, the content of the polyvinyl alcohol is not limited, but is usually 0.01% by weight to 100% by weight, preferably 0.10% by weight to 25% by weight, based on the weight of urea. For example, when compound A is a polyvinyl alcohol having a degree of saponification of usually 70 mol% to 85 mol%, preferably 78 mol% to 82 mol%, and an average degree of polymerization of usually 1000 to 2000, preferably 1500 to 1800, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.30 wt% to 25 wt%, based on the weight of urea.For example, when compound A is polyvinyl alcohol having a degree of saponification of usually 85 mol% to 95 mol%, preferably 86 mol% to 90 mol%, and an average degree of polymerization of usually 250 to 750, preferably about 500, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.30 wt% to 25 wt%, based on the weight of urea. For example, when compound A is polyvinyl alcohol having a degree of saponification of usually 85 mol% to 95 mol%, preferably 86 mol% to 90 mol%, and an average degree of polymerization of usually 750 to 1250, preferably 1000, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.10 wt% to 25 wt%, based on the weight of urea. For example, when compound A is polyvinyl alcohol having a degree of saponification of usually 85 mol% to 95 mol%, preferably 86 mol% to 90 mol%, and an average degree of polymerization of usually 1250 to 1750, preferably 1500, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.10 wt% to 25 wt%, based on the weight of urea. For example, when compound A is polyvinyl alcohol having a degree of saponification of usually 95 mol% or more, preferably 96 mol% or more, and an average degree of polymerization of usually 200 to 750, preferably 400 to 600, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.30 wt% to 25 wt%, based on the weight of urea. For example, when compound A is a polyvinyl alcohol having a degree of saponification of usually 95 mol% or more, preferably 96 mol% or more, and an average degree of polymerization of usually 750 to 1500, preferably 900 to 1000, the content of the polyvinyl alcohol is not limited, but is usually 0.01 wt% to 100 wt%, preferably 0.10 wt% to 25 wt%, based on the weight of urea.

[0023] Alternatively, for example, when compound A is a polyether, the weight ratio of urea to polyether (urea / polyether) is not limited, but is usually 1 or more, preferably 2 to 2000. For example, when compound A is a polyvinyl alcohol, the weight ratio of urea to polyvinyl alcohol (urea / polyvinyl alcohol) is not limited, but is usually 1 or more, preferably 4 to 2000.

[0024] Since the urea-containing liquid fertilizer of the present invention contains urea and the above-described compound A, the urea does not grow after precipitating as needle-like crystals in the liquid fertilizer, and the liquid fertilizer can be stored stably for a long period of time.

[0025] Water is a medium for dispersing urea and compound A in the urea-containing liquid fertilizer. Therefore, the content of water may vary depending on the contents of urea, compound A, and other components. The content of water is not limited, but is usually 10% by weight to 90% by weight, preferably 20% by weight to 80% by weight, based on the total weight of the urea-containing liquid fertilizer.

[0026] By using water as a medium for the urea-containing liquid fertilizer, the urea-containing liquid fertilizer of the present invention can be used in fertilization in a variety of situations.

[0027] In the urea-containing liquid fertilizer of the present invention, when urea exists as crystals, the average major axis of the urea crystals is usually 2 mm or less, preferably 1 mm or less. Note that, since the urea may be dissolved, there is no lower limit for the average major axis of the urea crystals.

[0028] The average long diameter of the urea crystals in a urea-containing liquid fertilizer can be calculated by measuring the long diameters passing through the centers of gravity of 10 crystals using an optical microscope and averaging the measurements.

[0029] In the urea-containing liquid fertilizer of the present invention, when urea is present as crystals, the average aspect ratio (major axis / minor axis) of the urea crystals is usually 1 to 20, preferably 1 to 15, more preferably 1 to 10, even more preferably 1 to 5, and particularly preferably 1 to 3.

[0030] The average aspect ratio of urea crystals can be calculated by measuring the major axis and minor axis passing through the center of gravity of 10 crystals and the aspect ratio (major axis / minor axis) using an optical microscope and averaging them.

[0031] The solubility of urea that can be used in urea-containing liquid fertilizers varies significantly depending on the temperature of the water in which the urea is dissolved, and so there is a problem in that it crystallizes and grows into needle-like crystals depending on the temperature during storage or fertilization. The urea-containing liquid fertilizer of the present invention does not suppress the crystallization of urea used as a nitrogen component, but rather precipitates urea and then suppresses the crystal growth during precipitation, thereby suspending and stabilizing the urea in water and further suppressing clogging of the nozzle of the device (for example, the inner diameter of the elliptical discharge part, minor axis approximately 3 mm x major axis approximately 7 mm) during fertilization.

[0032] Furthermore, the urea-containing liquid fertilizer of the present invention may further contain other components that can be generally used as fertilizer raw materials.

[0033] Other components include, but are not limited to, fertilizer components other than urea (nitrogen, phosphorus, potassium components other than urea), viscosity regulators, phase separation inhibitors (dispersants), chemical slow-release fertilizers, additional elements, other additives, etc.

[0034] Examples of fertilizer components other than urea include ammonia, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium sulfate, ammonium acetate, potassium nitrate, potassium chloride, potassium phosphate, potassium sulfate, phosphoric acid, and caustic potassium. Ammonia may be in the form of gas or liquid, or may be aqueous ammonia.

[0035] When the urea-containing liquid fertilizer of the present invention further contains a fertilizer component other than urea, the nitrogen content, phosphorus content, and potassium content of the fertilizer to be applied can be appropriately adjusted.

[0036] Examples of the viscosity adjuster and / or phase separation inhibitor include water-soluble polymers such as carboxymethylcellulose (CMC), guar gum, sodium alginate, xanthan gum, polyacrylamide, and starch; inorganic additives such as bentonite, attapulgite, white carbon, and diatomaceous earth; and polycarboxylic acid type polymer surfactants such as sodium acrylate homopolymer, sodium acrylate-hydroxyethyl methacrylate copolymer, sodium acrylate-sodium hydroxypropanesulfonate allyl ether copolymer, maleic acid homopolymer, and maleic acid-glycerin monoallyl ether copolymer.

[0037] By further containing a viscosity regulator and / or a phase separation inhibitor, the viscosity of the liquid fertilizer of the present invention can be appropriately adjusted according to the fertilization conditions, and the urea precipitated in the form of fine particles can be stably suspended in water.

[0038] Examples of chemical slow-release fertilizers include ureaform, acetaldehyde condensed urea (CDU), isobutyraldehyde condensed urea (IB), oxamide, guanylurea, and glyoxal urea.

[0039] By further containing a chemical slow-release fertilizer, the urea-containing liquid fertilizer of the present invention can have slow-release properties.

[0040] The additional elements may include calcium, silicon, sulfur, iron, zinc, copper, molybdenum, manganese, magnesium, boron, chlorine, and nickel.

[0041] Other additives may include, for example, carboxylic acids such as acetic acid and citric acid, chelating agents such as EDTA, nitrification inhibitors, pesticides, preservatives, and organic components such as bone meal, various fermentation waste liquids, and oil cake.

[0042] The content of each of the other components is not limited as long as each added component can appropriately exhibit its inherent effect, but is usually 0 to 90% by weight, preferably 0 to 50% by weight, based on the total weight of the urea-containing liquid fertilizer.

[0043] The total content of other components (the content of all other components added together) is not limited, but is usually 0.05 to 90% by weight, preferably 1 to 50% by weight, based on the total weight of the urea-containing liquid fertilizer.

[0044] The viscosity of the urea-containing liquid fertilizer of the present invention is not limited, but is usually from 100 cp to 10,000 cp, and preferably from 300 cp to 7,000 cp.

[0045] When the viscosity of the urea-containing liquid fertilizer of the present invention falls within the above range, the fertilizer can be applied efficiently.

[0046] The urea-containing liquid fertilizer of the present invention can be produced by a method known in the art, except that at least urea, the above-described compound A, and water are used as constituents.

[0047] The urea-containing liquid fertilizer of the present invention can be produced, for example, by adding urea and compound A to water, and mixing, for example, stirring, and dissolving.

[0048] The order of addition of urea, compound A, water, and possibly other components, the mixing device, etc. are not limited. For example, when the raw material is a solid raw material, the solid raw material can be crushed in advance, added to a predetermined amount of water together with other raw materials, and stirred and dispersed to produce a urea-containing liquid fertilizer. The crushing operation can be performed using a normal dry grinder or wet grinder, or a combination of them. Specifically, the order of addition of urea, compound A, and water can be, for example, adding urea to water, dissolving the urea, mixing uniformly, adding compound A and mixing, or adding compound A to water, dissolving compound A, mixing uniformly, adding urea and mixing, or adding water to a container charged with urea and compound A, mixing and dissolving.

[0049] It is preferable that urea is dissolved in water and mixed in the dissolved state with compound A. Therefore, it is preferable that urea is used at a concentration at which it dissolves in water (the concentration described above), for a time, for example, usually 1 minute to 60 minutes, and at a temperature, for example, usually 0° C. to 80° C. However, since the dissolution and precipitation of urea in water can occur due to equilibrium, the urea-containing liquid fertilizer of the present invention can be produced by adding urea and compound A to water and mixing them by, for example, stirring.

[0050] The present invention also relates to a method for inhibiting the growth of needle-like crystals of urea by adding the above-described compound A to a urea-containing liquid fertilizer.

[0051] In the method of inhibiting the growth of urea needle crystals in a urea-containing liquid fertilizer of the present invention, the urea-containing liquid fertilizer and compound A that can be used are as described above.

[0052] In the method for suppressing the growth of urea needle crystals in a urea-containing liquid fertilizer of the present invention, urea and the compound A described above are made to coexist in the urea-containing liquid fertilizer, thereby suppressing the deposition and growth of needle-shaped urea crystals in the liquid fertilizer and instead precipitating fine urea crystals.Therefore, the method of the present invention does not suppress the crystallization of urea used as a nitrogen component, but rather precipitates urea, suppresses the crystal growth during precipitation, and makes the crystals fine particles, stabilizing the suspension of urea in water, and further suppresses clogging of the nozzle of the device (for example, the inner diameter of the elliptical discharge part, the minor axis about 3 mm x major axis about 7 mm) during fertilization. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples, although the technical scope of the present invention is not limited to these examples.

[0054] I-1. Production and evaluation of urea-containing liquid fertilizers of the examples (1) 100 g of urea was added to 100 g of water heated to 40° C., and dissolved by stirring to prepare a urea-containing solution. (2) To the urea-containing solution prepared in (1), (i) polyethylene glycol 400, number average molecular weight of about 360 to 400 (Examples 1 to 4); (ii) polyethylene glycol 4000, number average molecular weight about 2700 to 3300 (Examples 5 to 9); (iii) polyethylene glycol 6000, number average molecular weight about 7300 to 9300 (Examples 10 to 17); (iv) polyethylene glycol 20,000, number average molecular weight about 15,000 to 25,000 (Examples 18 to 26), (Polyethylene glycol is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name.) (v) polyoxyethylene (23) lauryl ether (Examples 27 to 32), (Polyoxyethylene lauryl ether is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its product name.) (vi) Polyoxyethylene (20) sorbitan trioleate (Examples 33 to 40) (Polyoxyethylene sorbitan trioleate is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name), (vii) Polyvinyl alcohol (PVA): (vii-1) Saponification degree 78 mol% to 82 mol%, average polymerization degree 1500 to 1800 (Examples 41 to 49), (vii-2) Saponification degree: 86.0 mol% to 90.0 mol%, polymerization degree: about 500 (Examples 50 to 58), (vii-3) Saponification degree 86 mol% to 90 mol%, average polymerization degree 1000 (Examples 59 to 67), (vii-4) Saponification degree 86.0 mol% to 90.0 mol%, polymerization degree about 1500 (Examples 68 to 76), (vii-5) Saponification degree 96 mol+%, average polymerization degree about 400 to 600 (Examples 77 to 85), (vii-6) Saponification degree 96 mol+%, average polymerization degree about 900 to 1000 (Examples 86 to 94), (Various polyvinyl alcohols are manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (viii) Polyacrylic acid 5000 (Examples 95 to 102), (Polyacrylic acid is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (ix) hexamethylenediamine (Examples 103 to 106), (Hexamethylenediamine is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (x) Polyamide B-0 (Examples 107 to 109), (Polyamide B-0 is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) was added in an amount of 100 wt%, 50 wt%, 25 wt%, 12.5 wt%, 6.25 wt%, 3.125 wt%, 1.5625 wt%, 0.78125 wt%, 0.390625 wt%, 0.1953125 wt%, or 0.09765625 wt%, based on the total weight of urea, and the mixture was stirred to confirm the solubility of each organic compound, thereby preparing samples. (3) The sample prepared in (2) was allowed to stand at −5° C. for 24 hours to generate crystals, and the crystal morphology of the crystals was evaluated visually.

[0055] I-2. Production and evaluation of urea-containing liquid fertilizers as comparative examples In the production of the urea-containing liquid fertilizer of the embodiment, compound A is (I) Sodium alginate (Comparative Example 1), (Sodium alginate was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (II) Methylcellulose 4000 (Comparative Example 2), (Methylcellulose is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name.) (III) Carribon L-400 (Comparative Examples 3 to 6), (Carribon L-400 is an acrylic acid-based polycarboxylic acid type polymer surfactant manufactured by Sanyo Chemical Industries, Ltd. and is listed by its trade name.) (IV) Polypropylene glycol, triol type, 3000 (Comparative Examples 7 to 10), (Polypropylene glycol is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its product name.) A urea-containing liquid fertilizer was produced and evaluated in the same manner as in Example, except that the above-mentioned changes were made.

[0056] I-3. Results The results are shown in Tables 1 and 2.

[0057] [Table 1] TIFF2025013629000003.tif163167TIFF2025013629000004.tif217166TIFF2025013629000005.tif112154

[0058] [Table 2]

[0059] In the table, the numbers in the percentage of coarse crystals indicate the percentage of coarse crystals (residual urea) present when a certain amount of precipitate from urea-containing liquid fertilizer was collected and the degree of presence of coarse crystals of 2 mm or more was visually evaluated. Therefore, 4 indicates that the presence of coarse crystals could not be confirmed, 3 indicates that 0% to less than 25% by volume of coarse crystals were present relative to the volume of the urea-containing liquid fertilizer, 2 indicates that fine crystals were confirmed, but that coarse crystals were present in an amount of 25% or more by volume relative to the volume of the urea-containing liquid fertilizer, and 1 indicates that only coarse crystals were confirmed.

[0060] In the table, with regard to applicability as a liquid fertilizer, × indicates that it is not applicable as a liquid fertilizer, △ indicates that it is applicable as a liquid fertilizer, ○ indicates that it is highly applicable as a liquid fertilizer, and ◎ indicates that it is even more applicable as a liquid fertilizer.

[0061] From Tables 1 and 2, it was found that the precipitation of coarse crystals can be suppressed by adding even a small amount of compound A, which is an organic compound having a linear structure with 6 or more carbon atoms and having one or more functional groups selected from the group consisting of a hydroxyl group, a carbonyl group, an amino group, and an amide group, to a urea-containing liquid fertilizer. In particular, it was found that the effect of suppressing the precipitation of coarse crystals was more remarkable when polyethylene glycol or polyvinyl alcohol was used as compound A.

[0062] Although not shown in Table 2, a urea-containing liquid fertilizer consisting of water and urea was also produced. As a result, in the urea-containing liquid fertilizer consisting of water and urea, after fine needle-like crystals were precipitated, all of them grew into coarse needle-like crystals (evaluation result: 1), and the fertilizer was not suitable for use as a liquid fertilizer (evaluation result: ×).

[0063] II-1. Evaluation of the aspect ratio and major axis of fine precipitated crystals of urea-containing liquid fertilizer in the examples (1) 100 g of urea was added to 100 g of water heated to 40° C., and dissolved by stirring to prepare a urea-containing solution. (2) To the urea-containing solution prepared in (1), (i) polyethylene glycol 400, number average molecular weight about 360 to 400 (Example 110); (ii) polyethylene glycol 4000, number average molecular weight about 2700 to 3300 (Example 111); (iii) polyethylene glycol 6000, number average molecular weight about 7300 to 9300 (Example 112); (iv) polyethylene glycol 20,000, number average molecular weight about 15,000 to 25,000 (Example 113), (Polyethylene glycol is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name.) (v) polyoxyethylene (23) lauryl ether (Example 114), (Polyoxyethylene lauryl ether is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its product name.) (vi) polyoxyethylene (20) sorbitan trioleate (Example 115), (Polyoxyethylene sorbitan trioleate is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name.) (vii) Polyvinyl alcohol (PVA): (vii-1) Saponification degree 78 mol% to 82 mol%, average polymerization degree 1500 to 1800 (Example 116), (vii-2) Saponification degree 86.0 mol% to 90.0 mol%, polymerization degree about 500 (Example 117), (vii-3) Saponification degree 86 mol% to 90 mol%, average polymerization degree 1000 (Example 118), (vii-4) Saponification degree 86.0 mol% to 90.0 mol%, polymerization degree about 1500 (Example 119), (vii-5) Saponification degree 96 mol+%, average polymerization degree about 400 to 600 (Example 120), (vii-6) Saponification degree 96 mol+%, average polymerization degree about 900 to 1000 (Example 121), (Various polyvinyl alcohols are manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (viii) polyacrylic acid 5000 (Example 122); (Polyacrylic acid is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (ix) hexamethylenediamine (Example 123), (Hexamethylenediamine is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (x) Polyamide B-0 (Example 124), (Polyamide B-0 is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) was added in an amount of 50 wt %, 25 wt %, 12.5 wt % or 6.25 wt % based on the total weight of urea, and stirred to prepare samples. (3) The sample prepared in (2) was left to stand at -5°C for 24 hours to generate crystals, and the crystal morphology of the crystals was observed under an optical microscope. The average aspect ratio of the urea crystals was calculated by measuring the long and short diameters and the aspect ratio (long diameter / short diameter) of 10 crystals under an optical microscope and averaging them. The long diameter of the urea crystals was calculated by actually measuring the long diameter of 10 crystals and averaging them.

[0064] II-2. Evaluation of the aspect ratio and long diameter of fine precipitated crystals of urea-containing liquid fertilizers containing fertilizer components other than urea (1) 100 g of urea was added to 100 g of water heated to 40° C., and dissolved by stirring to prepare a urea-containing solution. (2) To the urea-containing solution prepared in (1), Polyethylene glycol 6000, number average molecular weight approx. 7300-9300 (Polyethylene glycol is a product of Fujifilm Wako Pure Chemical Industries, Ltd., and is listed by its trade name.) was added in an amount of 25% by weight based on the total weight of urea and stirred. (3) The compound A and urea-containing solution prepared in (2) is added as a fertilizer component. (xi) potassium chloride (Example 125), (Potassium chloride is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (xii) ammonium chloride (Example 126), (Ammonium chloride is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (xiii) ammonium sulfate (Example 127), (Ammonium sulfate is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (xiv) ammonium dihydrogen phosphate (Example 128), (Ammonium dihydrogen phosphate is a product of Fujifilm Wako Pure Chemical Industries, Ltd. and is listed by its product name.) (xv) ureaform (Example 129), (Ureaform is manufactured by Sumitomo Chemical Co., Ltd. and is a product name: Sumikaform.) was added in an amount of 25% by weight based on the total weight of urea and stirred to prepare a sample. (4) The sample prepared in (3) was left to stand at -5°C for 24 hours to generate crystals, and the crystal morphology of the crystals was observed under an optical microscope. The average aspect ratio of the urea crystals was calculated by measuring the long and short diameters and the aspect ratio (long diameter / short diameter) of 10 crystals under an optical microscope and averaging them. The long diameter of the urea crystals was calculated by actually measuring the long diameter of 10 crystals and averaging them.

[0065] II-3. Evaluation of the aspect ratio and major axis of precipitated crystals of urea-containing liquid fertilizer of Comparative Example 11 (1) 100 g of urea was added to 100 g of water heated to 40° C., and dissolved by stirring to prepare a urea-containing solution. (2) The urea-containing solution prepared in (1) was left to stand at -5°C for 24 hours to generate crystals, and the crystal morphology of the crystals was visually observed. The average aspect ratio of the urea crystals was calculated by measuring the long and short diameters and aspect ratio (long diameter / short diameter) of 10 crystals and averaging them. The long diameter of the urea crystals was calculated by measuring the long diameter of 10 crystals and averaging them.

[0066] II-4.Results The results are shown in Tables 3 to 5.

[0067] [Table 3] TIFF2025013629000008.tif170166TIFF2025013629000009.tif109170

[0068] [Table 4]

[0069] [Table 5]

[0070] From Tables 1 to 5, when an organic compound exhibiting water solubility and having a linear structure was used as compound A, the growth of urea needle crystals was suppressed and the morphology was changed to fine particles. In particular, when polyethers, polyvinyl alcohols, and polyamides were used as compound A, both the average aspect ratio and the major axis could be reduced, and the degree of suppression of crystal growth was good.

Claims

1. A urea-containing liquid fertilizer comprising urea, Compound A, a chemical slow-release fertilizer, and water, wherein Compound A is a polyethylene glycol having a linear structure with 6 or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxy group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmosphere and 20°C, Compound A has a number-average molecular weight of 200 to 30,000, and the content of Compound A is 0.01 wt % to 100 wt % relative to the weight of urea.

2. A urea-containing liquid fertilizer as described in claim 1, wherein the water content is 20% by weight to 80% by weight based on the total weight of the urea-containing liquid fertilizer.

3. 2. The urea-containing liquid fertilizer according to claim 1, wherein the urea content is 50% by weight or more based on the weight of water.

4. A urea-containing liquid fertilizer as described in claim 2, wherein the urea content is 50% by weight or more relative to the weight of water.

5. A urea-containing liquid fertilizer as described in claim 3, wherein the number average molecular weight of compound A is 2000 to 4000, and the content of compound A is 5% by weight to 100% by weight relative to the weight of urea.

6. A urea-containing liquid fertilizer as described in claim 3, wherein the number average molecular weight of compound A is 5,000 to 10,000, and the content of compound A is 0.5% by weight to 100% by weight relative to the weight of urea.

7. A urea-containing liquid fertilizer as described in claim 3, wherein the number average molecular weight of compound A is 10,000 to 30,000, and the content of compound A is 0.1% by weight to 100% by weight relative to the weight of urea.

8. A urea-containing liquid fertilizer as described in claim 1, wherein the chemical slow-release fertilizer is one or more selected from the group consisting of acetaldehyde condensed urea, isobutyraldehyde condensed urea, oxamide, guanylurea, and glyoxal urea.

9. Further containing one or more other components selected from the group consisting of fertilizer components other than urea, viscosity modifiers, phase separation inhibitors, additional elements, carboxylic acids, chelating agents, nitrification inhibitors, pesticides, preservatives, and organic components; the additional element is one or more selected from the group consisting of calcium, silicon, sulfur, iron, zinc, copper, molybdenum, manganese, magnesium, boron, chlorine, and nickel; the carboxylic acid is at least one selected from the group consisting of acetic acid and citric acid; The organic component is one or more selected from the group consisting of bone meal, fermentation waste liquid, and oil cake; The urea-containing liquid fertilizer according to claim 1.

10. The fertilizer component other than urea is one or more selected from the group consisting of ammonia, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium sulfate, ammonium acetate, potassium nitrate, potassium chloride, potassium phosphate, potassium sulfate, phosphoric acid, and caustic potash; the viscosity modifier and the phase separation inhibitor are at least one selected from the group consisting of carboxymethyl cellulose, guar gum, sodium alginate, xanthan gum, polyacrylamide, starch, bentonite, attapulgite, white carbon, diatomaceous earth, sodium acrylate homopolymer, sodium acrylate-hydroxyethyl methacrylate copolymer, sodium acrylate-sodium hydroxypropanesulfonate allyl ether copolymer, maleic acid homopolymer, and maleic acid-glycerin monoallyl ether copolymer; The urea-containing liquid fertilizer according to claim 9.

11. A urea-containing liquid fertilizer according to claim 9, wherein the total content of the chemical slow-release fertilizer and the other ingredients is 1 to 50% by weight based on the total weight of the urea-containing liquid fertilizer.

12. 2. The urea-containing liquid fertilizer according to claim 1, wherein urea is present in a crystalline form, the average long diameter of the crystals is 2 mm or less, and the average aspect ratio of the crystals is 1 to 20.

13. A urea-containing liquid fertilizer as described in claim 9, having a viscosity at the time of application of 300 mPa·s (cp) to 7000 mPa·s (cp).

14. A urea-containing liquid fertilizer comprising urea, compound A, ureaform, and water, wherein compound A is a polyethylene glycol having a linear structure with six or more carbon atoms, having one or more functional groups selected from the group consisting of a hydroxy group, a carbonyl group, an amino group, and an amide group, and having a solubility of 0.01 g or more in 100 g of water at 1 atmosphere and 20°C, wherein compound A has a number average molecular weight of 200 to 30,000, and the content of compound A is more than 25 wt% to 100 wt% relative to the weight of urea.

15. A urea-containing liquid fertilizer as described in claim 14, wherein the water content is 20% by weight to 80% by weight based on the total weight of the urea-containing liquid fertilizer.

16. A urea-containing liquid fertilizer as described in claim 14, wherein the urea content is 50% by weight or more relative to the weight of water.

17. A urea-containing liquid fertilizer as described in claim 15, wherein the urea content is 50% by weight or more relative to the weight of water.

18. A urea-containing liquid fertilizer as described in claim 16, wherein the number average molecular weight of compound A is 2,000 to 4,000.

19. A urea-containing liquid fertilizer as described in claim 16, wherein the number average molecular weight of compound A is 5,000 to 10,000.

20. A urea-containing liquid fertilizer as described in claim 16, wherein the number average molecular weight of compound A is 10,000 to 30,000.

21. The composition further comprises one or more other components selected from the group consisting of fertilizer components other than urea, viscosity modifiers, phase separation inhibitors, chemical slow-release fertilizers other than ureaform, additional elements, carboxylic acids, chelating agents, nitrification inhibitors, pesticides, preservatives, and organic components, the additional element is one or more selected from the group consisting of calcium, silicon, sulfur, iron, zinc, copper, molybdenum, manganese, magnesium, boron, chlorine, and nickel; the carboxylic acid is at least one selected from the group consisting of acetic acid and citric acid; The organic component is one or more selected from the group consisting of bone meal, fermentation waste liquid, and oil cake; 15. The urea-containing liquid fertilizer according to claim 14.

22. The fertilizer component other than urea is one or more selected from the group consisting of ammonia, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium sulfate, ammonium acetate, potassium nitrate, potassium chloride, potassium phosphate, potassium sulfate, phosphoric acid, and caustic potash; the viscosity modifier and the phase separation inhibitor are at least one selected from the group consisting of carboxymethyl cellulose, guar gum, sodium alginate, xanthan gum, polyacrylamide, starch, bentonite, attapulgite, white carbon, diatomaceous earth, sodium acrylate homopolymer, sodium acrylate-hydroxyethyl methacrylate copolymer, sodium acrylate-sodium hydroxypropanesulfonate allyl ether copolymer, maleic acid homopolymer, and maleic acid-glycerin monoallyl ether copolymer; The chemical slow-release fertilizer other than ureaform is one or more selected from the group consisting of acetaldehyde condensed urea, isobutyraldehyde condensed urea, oxamide, guanylurea, and glyoxal urea; 22. The urea-containing liquid fertilizer according to claim 21.

23. A urea-containing liquid fertilizer as described in claim 21, wherein the total content of ureaform and the other components is 1 to 50 weight % relative to the total weight of the urea-containing liquid fertilizer.

24. A urea-containing liquid fertilizer as described in claim 14, wherein urea is present in a crystalline form, the average long diameter of the crystals is 2 mm or less, and the average aspect ratio of the crystals is 1 to 20.

25. A urea-containing liquid fertilizer as described in claim 21, having a viscosity at the time of application of 300 mPa·s (cp) to 7000 mPa·s (cp).

26. A urea-containing liquid fertilizer described in any one of claims 1 to 25, which is used for mechanical fertilization.