Coated granular fertilizer and production method therefor

Abstract

The present invention relates to a coated granular fertilizer which comprises a granular fertilizer and a coating film covering the surface of the granular fertilizer, wherein the coating film comprises at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C). The α-olefin copolymer (A) satisfies the following (I). (I) A density, as obtained by a measurement method according to JIS K 6922-2, of 0.911-0.935 (g / cm3).

Description

Coated granular fertilizer and its manufacturing method

[0001] One embodiment of the present invention relates to a coated granular fertilizer and a method for producing the same.

[0002] Coated granular fertilizers, which are granular fertilizers coated with a film of resin or the like, are known. Coated granular fertilizers have been developed for the purposes of reducing the labor required for fertilization and achieving fertilizer efficacy in accordance with plant growth.

[0003] Coated granular fertilizers are stored in warehouses or outdoors until they are used, and may be subject to environmental changes over long periods of time. Furthermore, because coated granular fertilizers are used outdoors in paddy fields or fields, they are directly affected by environmental changes such as light (ultraviolet rays), heat (temperature), and moisture (humidity and rainfall). After application, the fertilizer must not only be durable against environmental changes, but also be able to maintain its fertilizing effect over a certain period of time. Thus, the coating of coated granular fertilizers is required to be weather-resistant and resistant to deterioration, and also to have excellent control over the leaching of fertilizer components.

[0004] For example, Patent Document 1 describes a coated granular fertilizer having a sigmoidal elution pattern with a strict elution inhibition period and excellent coating strength before use, with a density of 0.830 to 0.910 g / cm ３ The present invention discloses a coated granular fertilizer that is coated with a coating containing a resin component made of low molecular weight polyethylene and / or petroleum wax having specific physical properties and a powder whose main component is a sugar polymer or a derivative thereof.

[0005] However, many of these conventional coated granular fertilizers are coated with a coating of a persistent resin or the like, and the coating (also referred to as coating residue or coating shell) is difficult to disintegrate after the fertilizer components are leached out. Since the undisintegrated coating residue may float up and be washed out of the field, there is a demand for a coating that is difficult to disintegrate and float up, and that is easily decomposed in the environment.

[0006] Regarding coatings with improved disintegration properties, for example, Patent Document 2 discloses a coated granular fertilizer in which the coating quickly disintegrates, the coating is unlikely to float to the water surface in paddy fields, and is unlikely to remain in environments such as rivers and the sea. The granular fertilizer is coated with a coating containing one or more α-olefin (co)polymers (A) having a crystallization temperature (Tcmax) within a specific range, one or more waxes (B) having a crystallization temperature within a specific range, and one or more fillers (C), and in which the α-olefin (co)polymers (A) and the wax (B) are phase-separated in the microstructure of the fertilizer coating, and the wax (B) is finely dispersed.

[0007] Furthermore, for example, Patent Documents 3 and 4 disclose coated granular fertilizers having a coating that disintegrates and decomposes when exposed to sunlight or by oxidation.

[0008] Japanese Patent Application Laid-Open No. 2002-234790 International Publication No. 2012 / 147668 Pamphlet Japanese Patent Application Laid-Open No. 63-017286 Japanese Patent Application Laid-Open No. 5-201786

[0009] However, the technology of Patent Document 1 contains an elastomer with high elasticity or rubber-like elasticity, and therefore, although it has excellent sigmoidal elution controllability, the coating is difficult to disintegrate, and there is room for improvement in the disintegration and decomposition properties of the coating residue. The technology of Patent Document 2 exhibits rapid disintegration of the coating, but the coating is prone to deterioration in atmospheric environments and weather resistance is insufficient. Furthermore, the technology of Patent Document 2 incorporates hardened oil or solid fatty acid as the wax, which results in high hydrophilicity and insufficient elution controllability. The technologies of Patent Documents 3 and 4 are excellent in that the coating disintegrates quickly, but the coating is prone to deterioration in atmospheric environments and weather resistance is insufficient. Furthermore, in environments such as paddy fields or fields, the elution controllability is insufficient. In other words, it has been difficult with conventional technologies to achieve both disintegration and weather resistance.

[0010] Therefore, an object of one embodiment of the present invention is to provide a coated granular fertilizer having excellent coating disintegration properties and weather resistance, and also excellent elution controllability.

[0011] As a result of extensive research into the above-mentioned problems, the present inventors have found that the following configuration can solve the above-mentioned problems, and have thus completed the present invention. That is, one embodiment of the present invention is as follows.

[0012] [1] A coated granular fertilizer comprising a granular fertilizer and a coating covering the surface of the granular fertilizer, wherein the coating contains at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C), and the α-olefin copolymer (A) satisfies the following (I): (I) a density of 0.911 to 0.935 (g / cm) measured by a method conforming to JIS K 6922-2 ３). [2] The coated granular fertilizer according to [1], wherein the α-olefin copolymer (A) is linear low-density polyethylene (LLDPE). [3] The coated granular fertilizer according to [1] or [2], wherein the α-olefin copolymer (A) has a weight-average molecular weight of 20,000 to 150,000 as measured by GPC. [4] The coated granular fertilizer according to any of [1] to [3], wherein the hydrocarbon wax (B) has an acid value of less than 0.1 as measured by a method conforming to JIS K0070. [5] The coated granular fertilizer according to any of [1] to [4], wherein the hydrocarbon wax (B) has a contact angle with water of 90 to 110° as measured by the sessile drop method in the wettability test for substrate glass surfaces as measured by a method conforming to JIS R3257. [6] The coated granular fertilizer according to any of [1] to [5], wherein the hydrocarbon wax (B) is a saturated hydrocarbon. [7] The coated granular fertilizer according to any one of [1] to [6], wherein the hydrocarbon wax (B) has a weight-average molecular weight of 500 to 3,000 as measured by GPC. [8] The coated granular fertilizer according to any one of [1] to [7], wherein the filler (C) is at least one selected from talc, clay, and mica. [9] The coated granular fertilizer according to any one of [1] to [8], wherein the coating accounts for 1 to 20% by mass of 100% by mass of the coated granular fertilizer.

[10] The coated granular fertilizer according to any one of [1] to [9], wherein the α-olefin copolymer (A) accounts for 10.0 to 50.0% by mass of 100% by mass of the coating.

[11] The coated granular fertilizer according to any one of [1] to

[10] , wherein the mass ratio (A / B) of the α-olefin copolymer (A) to the hydrocarbon wax (B) is 0.5 to 5.0.

[12] A method for producing a coated granular fertilizer according to any one of [1] to

[11] , comprising: a step (I) of preparing a dispersion containing an α-olefin copolymer (A) containing at least one selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C); and a step (II) of, after the step (I), supplying the dispersion in a spray form to a fluidized granular fertilizer in a spouted tower type or fluidized bed type apparatus, thereby forming a coating on the surface of the granular fertilizer.

[0013] According to one embodiment of the present invention, it is possible to provide a coated granular fertilizer having excellent coating disintegration properties and weather resistance, and also excellent elution controllability.

[0014] Fig. 1 is a flow chart of an example of an apparatus for producing coated granular fertilizer. Fig. 2 is a squeezing disk of an example of an apparatus for producing coated granular fertilizer.

[0015] Next, a coated granular fertilizer and a method for producing the same according to one embodiment of the present invention will be specifically described.

[0016] <Coated Granular Fertilizer> A coated granular fertilizer according to one embodiment of the present invention comprises a granular fertilizer and a coating that coats the surface of the granular fertilizer, the coating comprising at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C), and the α-olefin copolymer (A) satisfies the following (I): (I) a density of 0.911 to 0.935 (g / cm) measured by a method conforming to JIS K 6922-2 ３ ). The coated granular fertilizer according to one embodiment of the present invention has excellent coating disintegration properties and weather resistance, and also has excellent elution controllability, and therefore can be suitably used outdoors in paddy fields, fields, and the like. In particular, when the coated granular fertilizer according to one embodiment of the present invention is used in paddy fields, it has excellent weather resistance and excellent elution controllability of fertilizer components, which leads to labor-saving in top dressing. Furthermore, the coated granular fertilizer according to one embodiment of the present invention has excellent coating disintegration properties, so that coating residue after elution of fertilizer components is less likely to float up, and it is possible to prevent the coating residue from flowing out of the field during puddling, etc.

[0017] <At least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE)> In the present invention, at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) is also referred to simply as "component (A)". A coated granular fertilizer according to one embodiment of the present invention comprises a granular fertilizer and a coating that coats the surface of the granular fertilizer, the coating containing component (A), and component (A) satisfying the following (I): (I) a density of 0.911 to 0.935 (g / cm) measured by a method conforming to JIS K 6922-2 ３ )

[0018] The density of component (A) is 0.911 to 0.935 (g / cm ３ ) and 0.915 to 0.925 (g / cm ３ ) is preferred. When the density of component (A) is within the above range, a coating film having an excellent balance between release controllability and disintegrability can be formed when used in combination with component (B) described below. If the density of component (A) is less than the above lower limit, the flexibility of component (A) increases, and the disintegrability of the coating film tends to be poor. If the density of component (A) is greater than the above upper limit, the rigidity increases, and therefore film formation defects such as pinholes are likely to occur during the production of the coated granular fertilizer, and release controllability tends to be poor.

[0019] The weight average molecular weight of component (A) measured by gel permeation chromatography (also simply referred to as "GPC") is preferably 20,000 to 150,000, more preferably 25,000 to 100,000, and even more preferably 30,000 to 70,000. Having a weight average molecular weight of component (A) within the above range is preferred because it provides good film-forming properties and excellent elution controllability.

[0020] The weight average molecular weight measured by GPC can be measured, for example, by using a high temperature GPC apparatus (PL-GPC210 model) manufactured by Polymer Laboratory Co., Ltd. equipped with two columns (PLgel MIXED-B) manufactured by the same company, using standard polyethylene manufactured by the same company as a calibration curve and orthodichlorobenzene as an eluent, at an oven temperature of 140° C. Alternatively, the measurement can be performed in accordance with, for example, JIS K 7252-1.

[0021] [Low-density polyethylene] In the present invention, low-density polyethylene refers to a synthetic resin belonging to the crystalline thermoplastic resin category, in which repeating units of ethylene are randomly branched and bonded together by radical polymerization of ethylene alone or ethylene and an α-olefin in a high-pressure reactor at several hundred to several thousand atmospheres using a radical initiator as a catalyst. In the present invention, low-density polyethylene is also simply referred to as "LDPE" (Low Density Polyethylene). Note that the low-density polyethylene in the present invention does not include linear low-density polyethylene, which will be described later.

[0022] The low-density polyethylene preferably has a density measured in accordance with JIS K 6922-2 of 0.911 to 0.935 (g / cm ３ ), more preferably 0.911 to 0.930 (g / cm ３ ), and more preferably 0.915 to 0.925 (g / cm ３ ) When the density of the low-density polyethylene is within the above range, film formation is easy and elution control is excellent, which is preferable. The melt flow rate (MFR) of the low-density polyethylene measured at 190°C under a load of 2.16 kg is preferably 0.05 to 50, more preferably 0.1 to 20. The melt flow rate can be measured in accordance with ISO 1133. When the melt flow rate of the low-density polyethylene is within the above range, film formability is good, resulting in fewer defects in the film and excellent elution control, which is preferable.

[0023] The weight-average molecular weight of the low-density polyethylene measured by GPC is preferably 30,000 to 150,000, more preferably 40,000 to 150,000. A weight-average molecular weight of the low-density polyethylene within the above range is preferred because it provides an excellent balance between elution controllability and coating disintegration properties. The weight-average molecular weight measured by GPC can be measured, for example, using a Polymer Laboratory high-temperature GPC apparatus (PL-GPC210 model) equipped with two columns (PLgel MIXED-B) manufactured by the same company, using the same company's standard polyethylene as a calibration curve and orthodichlorobenzene as an eluent, at an oven temperature of 140°C.

[0024] The melting point of the low-density polyethylene is preferably 100 to 130°C, more preferably 105 to 120°C, and can be measured, for example, in accordance with JIS K 6922-2. When the melting point of the low-density polyethylene is within the above range, it is easy to control the precipitation of the resin during film formation, and the film-forming properties are good, and the elution controllability is also excellent, which is preferable.

[0025] In the present invention, the density of the low-density polyethylene is 0.911 to 0.930 (g / cm ３ ) and the MFR of the low-density polyethylene measured at 190°C under a load of 2.16 kg is 0.05 to 50, since this tends to result in good film-forming properties, fewer defects in the coating, and excellent control over the elution of fertilizer components, it is more preferable.

[0026] [Linear Low-Density Polyethylene] In the present invention, linear low-density polyethylene refers to a synthetic resin belonging to the thermoplastic resin category obtained by copolymerizing repeating units of ethylene with a small amount of an α-olefin using a catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst in a low-pressure reactor at a pressure of several atmospheres to several tens of atmospheres. Linear low-density polyethylene has short-chain branches copolymerized with an α-olefin having 4 to 18 carbon atoms and has a linear molecular structure. In the present invention, linear low-density polyethylene is also simply referred to as "LLDPE" (Linear Low Density Polyethylene). Note that linear low-density polyethylene in the present invention does not include low-density polyethylene.

[0027] In the present invention, the term "α-olefin" refers to a linear or branched olefin having a carbon-carbon unsaturated double bond at the α-position. Examples of the α-olefin having 4 to 18 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 4-methyl-1-hexene. Among these, 1-butene, 1-hexene, 4-methyl-1-pentene, or 1-octene is preferred as the α-olefin having 4 to 18 carbon atoms because of their excellent elution controllability.

[0028] Specific examples of linear low-density polyethylene include copolymers of ethylene and an α-olefin, such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4 methylpentene 1 copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-hexene copolymer, and ethylene-butene-hexene copolymer. Among these, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-4 methylpentene 1 copolymer are preferred because of their excellent elution controllability.

[0029] The linear low-density polyethylene preferably has a density measured in accordance with JIS K 6922-2 of 0.911 to 0.935 (g / cm ３ ), more preferably 0.915 to 0.925 (g / cm ３ ) When the density of the linear low-density polyethylene is within the above range, it is preferable because film formation is easy and elution control is excellent. The melt flow rate (MFR) of the linear low-density polyethylene measured at 190°C under a load of 2.16 kg is preferably 0.1 to 50, more preferably 1 to 30, and even more preferably 10 to 30. When the melt flow rate of the linear low-density polyethylene is within the above range, it is preferable because film-formability is good, there are few defects in the film, and elution control is excellent.

[0030] The weight-average molecular weight of the linear low-density polyethylene measured by GPC is preferably 25,000 to 90,000, more preferably 30,000 to 70,000. A weight-average molecular weight of the linear low-density polyethylene within the above range is preferred because it provides an excellent balance between elution controllability and film disintegration properties. In the present invention, the linear low-density polyethylene preferably has a melting point of 100 to 130°C, more preferably 110 to 125°C. A melting point of the linear low-density polyethylene within the above range is preferred because it is easy to control resin precipitation during film formation, resulting in good film-formability and excellent elution suppression. The density, MFR, weight-average molecular weight, and melting point of the linear low-density polyethylene can be measured using the same methods as for low-density polyethylene.

[0031] In the present invention, it is more preferable that the linear low-density polyethylene has a density of 0.915 to 0.925 and a weight-average molecular weight of 30,000 to 70,000, since this provides excellent disintegration properties and weather resistance to the coating while also providing excellent elution controllability.

[0032] Component (A) may contain low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or both. However, from the viewpoint of achieving an excellent balance between dissolution controllability and disintegrability and reducing the amount of difficult-to-decompose resin used, component (A) is preferably linear low-density polyethylene (LLDPE).

[0033] The coated granular fertilizer according to one embodiment of the present invention preferably contains 10.0% by mass or more of component (A) relative to 100% by mass of the coating, more preferably 15.0% by mass or more, and even more preferably 18.5% by mass or more. When 100% by mass of the coating contains 10.0% by mass or more of component (A), the coating tends to have fewer defects such as pinholes and exhibit excellent initial release controllability.

[0034] The coated granular fertilizer according to one embodiment of the present invention preferably contains 50.0% by mass or less of component (A) relative to 100% by mass of the coating, more preferably 42.1% by mass or less, and even more preferably 35.4% by mass or less, because this allows for a reduction in the amount of α-olefin copolymer in the coating and a reduction in the environmental load. If the coating contains more than 50.0% by mass of component (A) relative to 100% by mass of the coating, disintegration properties tend to deteriorate.

[0035] <Hydrocarbon wax (B) having a melting point of 80°C or higher> In the present invention, the hydrocarbon wax (B) having a melting point of 80°C or higher is also referred to simply as "component (B)." A coated granular fertilizer according to one embodiment of the present invention comprises a granular fertilizer and a coating that coats the surface of the granular fertilizer, and the coating contains a hydrocarbon wax (B) having a melting point of 80°C or higher, preferably 100°C or higher.

[0036] Examples of component (B) include saturated hydrocarbons and unsaturated hydrocarbons, with saturated hydrocarbons being preferred from the viewpoints of excellent oxidation stability of the coating and excellent weather resistance. Saturated hydrocarbons can be classified into linear (normal), branched (iso), and cyclic (cyclo) types based on their molecular structure, with linear hydrocarbons being preferred from the viewpoints of high crystallinity and oxidation stability. Note that component (B) does not include waxes having hydroxyl or carboxy groups, such as castor wax and oxidized modified polyethylene wax. Furthermore, component (B) does not include waxes having carbonyl groups, such as ester wax. That is, component (B) does not include waxes having hydroxyl, carboxy, or carbonyl groups.

[0037] Specific examples of component (B) include polyethylene wax, microcrystalline wax, Fischer-Tropsch wax, and polypropylene wax. Among these, from the viewpoint of affinity with component (A), component (B) is preferably at least one selected from polyethylene wax, microcrystalline wax, and Fischer-Tropsch wax, and polyethylene wax is more preferred from the viewpoint of cost, since it is industrially produced stably and can be obtained relatively inexpensively. Component (B) may be used alone or in combination of two or more.

[0038] In the present invention, when the melting point of the hydrocarbon wax is 80°C or higher, resin precipitation can be easily controlled during film formation, resulting in good film-forming properties and excellent elution suppression. Furthermore, when the melting point of the hydrocarbon wax is 100°C or higher, the film can achieve both disintegration and weather resistance, and elution control tends to be good, which is preferable. When the melting point of the hydrocarbon wax is less than 80°C, the quality of the film changes due to temperature changes during storage, making it difficult to control the elution of fertilizer components, and storage stability tends to be poor. Furthermore, when the melting point of the hydrocarbon wax is less than 80°C, the difference in melting point from component (A) is large, which tends to result in poor precipitation behavior during film formation and poor film-forming properties. The melting point of component (B) can be measured, for example, using a differential scanning calorimeter (DSC, Shimadzu DSC-60) to obtain an endothermic curve when 5±0.5 mg of a sample is heated to 200°C at a rate of 10°C / min and melted, and the peak temperature (Tm) of the endothermic curve can be measured.

[0039] [Acid value] The acid value indicates the amount of free fatty acids in fats and oils, and is expressed as the number of milligrams of potassium hydroxide required to neutralize the free fatty acids contained in 1 g of fats and oils. In the present invention, the acid value of component (B) measured according to JIS K0070 is preferably less than 0.1, more preferably 0. If the acid value is 0.1 or more, the hydrophilicity of the coating film may increase, resulting in poor elution controllability. Furthermore, if the acid value is 0.1 or more, carbonyl groups and the like may promote deterioration of the coating film, resulting in poor oxidation stability.

[0040] [Contact Angle] In the present invention, component (B) preferably has a contact angle with water of 90 to 110°, more preferably 95 to 105°, as measured by the sessile drop method of testing the wettability of substrate glass surfaces according to JIS R 3257. When component (B) has a contact angle within the above range, the hydrophobicity of the coating tends to be high and the elution controllability tends to be excellent, which is preferable.

[0041] [Weight-Average Molecular Weight] In the present invention, the weight-average molecular weight of component (B) measured by GPC is preferably 500 to 3,000, more preferably 600 to 2,000. If the weight-average molecular weight of component (B) exceeds 3,000, the disintegration properties of the coating tend to deteriorate. If the weight-average molecular weight of component (B) is less than 500, poor precipitation during coating tends to cause defects in the coating, resulting in poor elution. A weight-average molecular weight of component (B) within the above range is preferable because it allows the formation of a coating that exhibits an excellent balance between elution controllability and disintegration properties. In the present invention, the weight-average molecular weight measured by GPC can be measured, for example, by the same method as for component (A) described above.

[0042] [Saponification value] The saponification value indicates the amount of free fatty acids and esters in fats and oils, and is expressed as the number of mg of potassium hydroxide required to saponify the esters and neutralize the free fatty acids contained in 1 g of fats and oils. In the present invention, component (B) preferably has a saponification value of less than 0.1, more preferably 0, as measured by the saponification value measurement method specified in JIS K0070. If the saponification value is 0.1 or more, the hydrophilicity of the coating film may increase, resulting in poor elution controllability. Furthermore, if the saponification value is 0.1 or more, carbonyl groups and the like may promote deterioration of the coating film, resulting in poor oxidation stability.

[0043] The coated granular fertilizer according to one embodiment of the present invention preferably contains 5.0% by mass or more of component (B) relative to 100% by mass of the coating, more preferably 8.9% by mass or more, and even more preferably 10.0% by mass or more. When the component (B) is contained in 100% by mass of the coating, the coating tends to have excellent disintegration properties, which is preferable.

[0044] The coated granular fertilizer according to one embodiment of the present invention preferably contains 25.0% by mass or less of component (B) relative to 100% by mass of the coating, more preferably 20.3% by mass or less, and even more preferably 17.0% by mass or less. When the component (B) is contained in more than 25.0% by mass relative to 100% by mass of the coating, the disintegration property tends to be high, but the strength of the coating tends to be insufficient, resulting in poor release controllability.

[0045] In one embodiment of the present invention, the coating contains at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) having a specific density, and a hydrocarbon wax (B) having a melting point of 80°C or higher. This allows the coating to achieve both disintegration resistance and weather resistance, and also provides excellent elution control. While the reason for this is unclear, the inventors believe that the combined use of a high-molecular-weight component (A) and a low-molecular-weight component (B) can impart disintegration properties to the coating. It is difficult for a coating that is merely prone to disintegration to exhibit excellent elution control. However, the inventors speculate that the inclusion of specific components (A) and (B) in the coating increases the affinity between components (A) and (B), which have linear structural characteristics, and increases the crystalline density of the coating, resulting in excellent elution control of the coating.

[0046] In the coated granular fertilizer according to one embodiment of the present invention, the combined use of components (A) and (B) in the coating provides a coating that exhibits superior elution suppression, elution control, and disintegration properties compared to the use of component (A) alone. Furthermore, the combined use of components (A) and (B) in the coating tends to significantly improve weather resistance. While the reasons for this are unclear, the inventors speculate that the combined use of components (A) and (B) enhances the crystallinity of the coating, making it more difficult for oxygen in the environment to penetrate into the coating, and that the absence of oxygen atoms, which are thought to be the starting point for oxidation, in the molecular structure of the coating makes the coating less susceptible to oxidative degradation, resulting in superior weather resistance. It is believed that these combined factors are responsible for the excellent effects of the present invention.

[0047] <Filler (C)> A coated granular fertilizer according to one embodiment of the present invention comprises a granular fertilizer and a coating covering the surface of the granular fertilizer, and the coating contains a filler (C). By including the filler (C) in the coating, the coated granular fertilizer according to one embodiment of the present invention can provide a degradable coated granular fertilizer that can control leaching, particularly effectively suppress initial leaching. Examples of the filler (C) include inorganic fillers such as talc, clay, mica, alumina, bentonite, silica, diatomaceous earth, sulfur powder, titanium oxide, calcium carbonate, and calcium sulfate. Among these, the filler (C) is preferably at least one selected from talc, clay, and mica, and more preferably talc, because of its excellent effect in suppressing initial leaching. The talc preferably has an average particle size of 0.1 to 40 μm, more preferably 0.2 to 30 μm, as calculated using a particle size distribution analyzer using a laser diffraction method.

[0048] If the particle size of the filler (C) is less than 0.1 μm, the filler tends to aggregate during film formation, resulting in a substantially large particle size. If the particle size of the filler (C) is more than 40 μm, the film is more likely to have defects, and the elution controllability may be reduced.

[0049] The coated granular fertilizer according to one embodiment of the present invention preferably contains 5 to 80 mass %, more preferably 20 to 75 mass %, and even more preferably 30 to 65 mass % of the filler (C) relative to 100 mass % of the coating. The filler (C) may be used singly or in combination of two or more types.

[0050] <Coating> A coated granular fertilizer according to one embodiment of the present invention comprises a granular fertilizer and a coating that coats the surface of the granular fertilizer, and the coating contains a component (A), a component (B), and a filler (C). In the coated granular fertilizer according to one embodiment of the present invention, the mass ratio (A / B) of the component (A) to the component (B) in 100 mass% of the coating is preferably 0.5 to 5.0, and more preferably 1.0 to 3.2, in order to achieve an excellent balance between coating strength and elution controllability.

[0051] [Other Components] The coated granular fertilizer according to one embodiment of the present invention may contain other components in addition to the above-mentioned components, as long as the effects of the present invention are not impaired. The other components preferably account for 0.01 to 15 mass%, more preferably 0.01 to 10 mass%, of 100 mass% of the coating. Examples of other components that can be used include organic substances, organometallic compounds, surfactants, and bulking agents (excluding components corresponding to the filler (C) above).

[0052] Specific examples of organic substances include polysaccharides and their derivatives. Examples of polysaccharides and their derivatives include cellulose, agar, starch (also called starch), chitin and its derivatives, and chitosan and its derivatives. Among these, starch is inexpensive and preferred as the organic substance. Examples of starch that can be used include starches derived from corn, tapioca, wheat, potato, rice, and sweet potato. Processed starches, such as pregelatinized starch, and silicone-treated starch, in which the surface of starch is treated with a silicone resin or the like to improve dispersibility and fluidity, can also be used. The particle size of the organic substance is preferably 100 μm or less, more preferably 1 to 50 μm. A particle size within the above range is preferred because it is less likely to cause problems such as peeling of the coating during film formation due to excessive particle size or clogging of spray nozzles with the coating material.

[0053] Specific examples of the organometallic compound include organometallic complexes, organic acid metal salts, etc. Among organometallic complexes, iron complexes such as iron acetylacetonate, iron acetonylacetonate, iron dialkyldithiocarbamate, dithiophosphate, xanthate, and benzthiazole, and iron carboxylates such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, behenic acid, oleic acid, linoleic acid, and linolenic acid are preferred because they facilitate photodecomposition control of the polymer in the coating, and among these, iron stearate and iron acetylacetonate are more preferred.

[0054] Specific examples of surfactants include water-soluble substances such as polyethylene glycol, polypropylene glycol, polyalkylene glycols obtained by copolymerization of ethylene glycol and propylene glycol, polyvinyl alcohol, and the like; ether-type nonionic surfactants such as polyethylene glycol-alkyl ethers and polyethylene glycol-branched alkyl ethers; ester-type nonionic surfactants such as polyethylene glycol-alkyl esters and polyethylene glycol-branched alkyl esters; cationic surfactants; anionic surfactants; amphoteric surfactants; and mixtures thereof.

[0055] In the coated granular fertilizer according to one embodiment of the present invention, the coating preferably contains substantially no thermoplastic elastomer, such as ethylene-vinyl acetate copolymer (EVA). When the coating contains a thermoplastic elastomer, the elasticity and flexibility of the coating improve, but the disintegration properties of the coating tend to deteriorate. Therefore, it is preferable that the coating is substantially free of thermoplastic elastomer. "Substantially free of thermoplastic elastomer" means that, although thermoplastic elastomers present as impurities in each component may be contained in the coating, no thermoplastic elastomer is intentionally added. "Substantially free of thermoplastic elastomer" typically means that the coating contains 0 to 0.009% by mass, preferably 0 to 0.005% by mass, of thermoplastic elastomer per 100% by mass of the coating. The other components may be used alone or in combination of two or more.

[0056] [Disintegrability] The disintegrability of the coating in a coated granular fertilizer can be determined by using the coating (coating shell) dried after eluting only the fertilizer components from the coated granular fertilizer. Disintegrability can be evaluated, for example, by putting the coated granular fertilizer into water to elute the fertilizer components, drying it in a ventilated dryer set at 45°C for 30 days, putting 25 particles of the resulting hollow coating shell into sea sand (20 to 35 mesh) being stirred at 300 rpm, recovering the particles after 5 minutes, and calculating the disintegration rate according to the following formula (1):

[0057] Disintegration rate = (Number of particles fed - Number of particles recovered) / Number of particles fed × 100 Equation (1)

[0058] In the present invention, a higher disintegration rate means better disintegrability. In the present invention, the disintegration rate is preferably 1% or more, more preferably 20% or more, and even more preferably 40% or more.

[0059] [Weather resistance] The weather resistance of the coating of a coated granular fertilizer refers to the property of resisting the phenomenon in which the coating is subjected to oxidation degradation due to the influence of the outdoor atmospheric environment, resulting in a decrease over time in the initial performance, etc. Test methods for the weather resistance of the coating of a coated granular fertilizer include an atmospheric exposure test conducted in an atmospheric environment and an accelerated exposure test using an indoor testing machine with specific environmental factors in the atmospheric environment as the main factors. In the present invention, the accelerated exposure test is preferred as the weather resistance test method, since it is easy to standardize the test conditions.

[0060] An example of an accelerated exposure test is a test conforming to JIS K 7350-1:2020 (ISO 4892-1:2016). Examples of indicators of the weather resistance of a coating include the rate of change in carbonyl index (CI value), the rate of change in weight average molecular weight of the coating, and the rate of change in weight of the coating. However, the rate of change in weight of the coating is preferred because it is a simple measurement method and makes it easy to directly observe the amount of coating that has evaporated away. The rate of change in weight of the coating can be evaluated, for example, by calculating it from the initial coating weight according to the following formula (2):

[0061] Weight change rate (%)={(initial coating weight−coating weight after accelerated exposure test) / initial coating weight}×100 Equation (2)

[0062] In the present invention, a lower weight change rate of the coating means better weather resistance. In the present invention, the weight change rate of the coating is preferably 10% or less, more preferably -5% or less, of the initial coating weight.

[0063] [Controllability of elution of fertilizer components] The controllability of elution of fertilizer components in a coated granular fertilizer can be evaluated, for example, by the elution rate (%) of the fertilizer components when the coated granular fertilizer is immersed in water. The elution rate (%) of the fertilizer components can be expressed by the following formula (3).

[0064] Dissolution rate (%) = (mass of dissolved fertilizer components) / (mass of fertilizer components contained in coated granular fertilizer) × 100 Formula (3)

[0065] The elution rate of fertilizer components can be measured, for example, by leaving the coated granular fertilizer stationary in water at 25°C and quantitatively analyzing the fertilizer components eluted into the water over time. Examples of methods for quantitatively analyzing fertilizer components include the method proposed by the Environmental Technology Research Institute of the Ministry of Agriculture, Forestry and Fisheries ("Detailed Explanation of Fertilizer Analysis Methods," edited by Koshino Masayoshi, 1988, published by Yokendo). Fertilizer components are generally water-soluble, and if there is a defect in the coating, many of the fertilizer components will elute upon application, resulting in insufficient elution controllability.

[0066] In the coated granular fertilizer according to one embodiment of the present invention, the release controllability is such that the release rate in water at 25°C on 28 days is preferably less than 80%, more preferably less than 50%, even more preferably less than 20%, even more preferably less than 10%, and even more preferably less than 5%, in accordance with the above-mentioned "Detailed Fertilizer Analysis Method." Note that in the present invention, a release rate on 28 days of more than 0% is preferable because it means that the fertilizer components have been released.

[0067] [Coating Rate] In a coated granular fertilizer according to one embodiment of the present invention, the coating rate can be calculated by the following formula (4): Coating rate (%) = (mass of coating) / (mass of coated granular fertilizer) × 100 Formula (4) The coating rate is preferably 1 to 20%, more preferably 2 to 15%, and even more preferably 4 to 14%. That is, the coating preferably accounts for 1 to 20% of 100% by mass of the coated granular fertilizer, more preferably 2 to 15%, and even more preferably 4 to 14%. A coating rate within the above range is preferable because it provides excellent control over the elution components of the fertilizer. The thickness of the coating can be appropriately selected depending on the type and composition of the coating material, the size of the fertilizer particles to be coated, and the intended elution pattern of the fertilizer components, but is preferably 10 to 100 μm on average, and more preferably 20 to 70 μm.

[0068] <Granular Fertilizer> The granular fertilizer used in one embodiment of the present invention may be any fertilizer containing one or more fertilizer components, such as nitrogen, phosphoric acid, or potassium. Specific examples include nitrogenous fertilizers, phosphate fertilizers, and potassium fertilizers, as well as fertilizers containing trace elements essential for plants, such as calcium, magnesium, sulfur, iron, manganese, and boron, as well as silicon, as necessary. Fertilizers containing nitrification inhibitors, pesticide components, and the like are also acceptable. Among these, nitrogenous fertilizers containing ammonium sulfate, urea, and ammonium nitrate, which have high water solubility and are prone to environmental runoff, potassium fertilizers containing potassium sulfate and potassium chloride, and chemical fertilizers containing urea, ammoniacal nitrogen, and nitrate nitrogen are preferred, with urea being more preferred due to its low unit price per fertilizer component. The fertilizer components may be used alone or in combination of two or more.

[0069] The granular fertilizer may contain other components within the scope of the present invention, such as carriers, binders, surfactants, blackstrap molasses, animal oils, vegetable oils, hydrogenated oils, fatty acids, fatty acid metal salts, paraffin, wax, and glycerin, and these may be used alone or in combination of two or more.

[0070] The method for producing the granular fertilizer used in one embodiment of the present invention is not particularly limited, and the granular fertilizer can be produced using a known granulation method, such as a fluidized bed granulation method, a tumbling granulation method, a coating granulation method, or an adsorption granulation method.

[0071] The shape of the granular fertilizer used in one embodiment of the present invention is not particularly limited, but is preferably spherical from the viewpoint of facilitating uniform coating of the surface with the coating material. Specifically, the shape of the granular fertilizer preferably has a circularity coefficient calculated by the following formula (5) of 0.7 or more and 1 or less, more preferably 0.75 or more and 1 or less, and most preferably 0.8 or more and 1 or less. The maximum value of the circularity coefficient is 1, and the closer to 1 the value is, the closer the particles of the granular fertilizer are to a perfect circle, and the smaller the circularity coefficient is as the particle shape deviates from a perfect circle. Circularity coefficient = {(4π × projected area of ​​particle) / (length of outline of particle projection)} ２} ...Formula (5)

[0072] In the present invention, the granular fertilizer preferably has an average particle size of 1 to 10 mm, more preferably 2 to 5 mm. It is preferable that the average particle size of the granular fertilizer is within the above range, since it is easy to coat the surface of the granular fertilizer to prepare a coated granular fertilizer. As the granular fertilizer, commercially available granular fertilizers or manufactured granular fertilizers can be used, and the average particle size can be adjusted to a desired value by using a sieve or the like as appropriate. In the present invention, the average particle size refers to the average particle size calculated by a particle size distribution analyzer such as dynamic image analysis.

[0073] In the present invention, examples of commercially available granular fertilizers that can be used include urea (manufactured by PETRONAS Fertilizer (Kedah) Sdn. Bhd.) as granular urea, ammonium phosphate (manufactured by Central Green Co., Ltd.) as granular ammonium phosphate, and potassium sulfate (manufactured by Asahi Agria Co., Ltd.) as granular potassium phosphate.

[0074] <Method for producing coated granular fertilizer> A method for producing a coated granular fertilizer according to one embodiment of the present invention includes: a step (I) of preparing a dispersion containing at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C); and a step (II) of, after the step (I), supplying the dispersion in a spray form to the granular fertilizer in a fluidized state in a spouted tower type or fluidized bed type apparatus, thereby forming a coating on the surface of the granular fertilizer.

[0075] The coated granular fertilizer according to one embodiment of the present invention uses components (A), (B), and a filler (C) as coating constituents, but can otherwise be produced in the same manner as general coated granular fertilizers. For example, a preferred production method includes the steps of preparing a dispersion, solution, or molten liquid containing the coating constituents, and supplying the dispersion in a sprayed form to fluidized granular fertilizer in a spouted tower or fluidized bed apparatus, thereby forming a coating on the surface of the granular fertilizer. From the viewpoint of excellent control of initial dissolution, a production method using a dispersion or solution is preferable to a production method using a molten liquid.

[0076] To fluidize the granular fertilizer, for example, the granular fertilizer may be introduced into a jetting device to generate a jet. To achieve this, a jet tower or fluidized bed device may be used, with the jet tower being preferred. Schematic diagrams of the jet tower device used in the production method according to one embodiment of the present invention are shown in Figures 1 and 2.

[0077] Hereinafter, one embodiment of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" in the following examples means % by mass.

[0078] <Material Preparation> In the examples and comparative examples, coated granular fertilizers were prepared using commercially available products. The commercially available products and their physical properties are as follows. In the tables, "MW" refers to the weight-average molecular weight measured by GPC, and "MFR" refers to the melt flow rate measured at 190°C under a load of 2.16 kg.

[0079] ・PO1: Linear low-density polyethylene (LLDPE) ・PO2: Linear low-density polyethylene (LLDPE) ・PO3: Linear low-density polyethylene (LLDPE) ・PO4: Linear low-density polyethylene (LLDPE) ・PO5: Linear low-density polyethylene (LLDPE) ・PO6: High-density polyethylene (HDPE) ・PO7: Low-density polyethylene (LDPE)

[0080] ・WAX1: Polyethylene wax (PEWAX) ・WAX2: Microcrystalline wax ・WAX3: Fischer-Tropsch wax ・WAX4: Castor wax (CW) ・WAX5: Oxidized modified polyethylene wax (oxidized PEWAX) ・WAX6: Polyethylene wax (PEWAX) ・WAX7: ​​Fischer-Tropsch wax

[0081]

[0082]

[0083] Granular fertilizer: Granular urea: Circularity coefficient 0.9 Filler: Talc: Average particle size 10 μm Other ingredients: Starch (corn starch: particle size 12-18 μm), SA (hexaoxyethylene nonylphenyl ether (surfactant)), Fe (iron (III) stearate: reagent grade, purity 99% or more)

[0084] Examples 1 to 15, Comparative Examples 1 to 6 Apparatus for Producing Coated Granular Material The configuration of the apparatus for producing coated granular fertilizer 1 used in the examples and comparative examples was the same as that shown in the flow sheet of FIG. 1 . The entrained flow tower 1 had a tower diameter (inner diameter) of 1,300 mm, a height of 8,500 mm, and a cone angle of 50 degrees, and had a granular fertilizer inlet 15 and a coated granular fertilizer outlet 13. The spray nozzle 2 was a Furucon type single-fluid spray nozzle, and 3 was the granular fertilizer (core material). 6 was a solid-gas separator, and 7 was a condenser. 8 was a blower (Roots type), and 12 was a heater. 9 was a coating mixture preparation tank (dissolution tank) equipped with an agitator, and 10 was a liquid transfer pump (diaphragm type). 14 was a guide tube (diameter 300 mm, length 1,760 mm, fluororesin coated), and 11 was a rectifier. 21 was a throttle disk. Details of the throttle disk 2 are shown in FIG. 2. 2, the diameter was 154 mm, the inner diameter of the nozzle holes 23 was 45 mm, the number of nozzle holes was 4 (opening ratio 34%), and a spray nozzle 2 was provided at the center of each nozzle hole 23. The spray nozzles 2 were arranged on a circle with a diameter of 95 mm centered on the center of the throttle disk 21.

[0085] <Method for Producing Coated Granular Fertilizer> Coated granular fertilizer was produced using the above-described production apparatus by the following method. A heated airflow flows from the bottom to the top of the entrained flow tower 1, passes through the solid-gas separator 6, and is cooled in the condenser 7 to condense and recover the organic solvent. The airflow that passed through the condenser 7 is circulated so that it passes through the blower 8, heater 12, where it is heated and introduced again to the entrained flow tower 1 as a high-temperature airflow. First, air maintained at an airflow temperature of 150°C at the nozzle 23 is sent to the entrained flow tower 1 using the blower 8, while the granular fertilizer (core material) 3 is introduced through the granular fertilizer inlet 15, bringing the granular fertilizer 3 into a spouted state. At this time, the flow rate and temperature of the heated airflow were adjusted so that the temperature of the granular fertilizer was 65±2°C. The airflow rate was adjusted by measuring with a flow meter installed between the blower 8 and the rectifier 11, and the temperature of the heated airflow was adjusted by measuring the temperature of the granular fertilizer and the temperature at the outlet of the entrained flow tower. Circulating air volume: 3,000 m ３ / h, and the amount of granular fertilizer input was 1,000 kg. Coated granular fertilizers were produced using the above-mentioned production apparatus according to the compositions shown in Table 3. Coated granular fertilizers were obtained without any problems in production in Examples and Comparative Examples 1 to 5. In Comparative Example 6, clogging of the spray nozzle occurred during production, and coated granular fertilizer could not be obtained.

[0086]

[0087] [Covering rate] The covering rate was calculated by the above-mentioned formula (4). The mass of the coating material was calculated by subtracting the mass of the granular fertilizer before coating from the mass of the coated granular fertilizer. The average value of 350 pieces of the coated granular fertilizer or 350 pieces of the granular fertilizer before coating was used for each mass.

[0088] [Weather resistance] Measurement method Each of the coated granular fertilizers obtained in the Examples and Comparative Examples was placed in water to allow the fertilizer components to elute, and then dried for 30 days in a ventilated dryer set at 45°C to obtain a coating shell. The weight of 300 coated shells was measured and the initial value was recorded. The coated shells were then placed in an accelerated weathering test device (Toyo Seiki, Suntest XLS+, 1700W xenon lamp) and exposed to an irradiation intensity of 550W / m ２ The accelerated exposure test was carried out under the conditions of a wavelength of 300 to 800 nm (daylight filter), a radiation intensity of 58°C (black standard thermometer (BST)), and a treatment time of 240 hours. The weight of the coating shell was measured using a precision balance (AUX320).

[0089] Evaluation Weather resistance was evaluated according to the following criteria, using the weight change rate of the coating calculated from the above formula (2) as an index. The weight change rate (%) and the weather resistance evaluation are shown in Table 4.

[0090] ○: The weight change rate from the initial value is 0% to minus 10% or less, and weather resistance is excellent. ×: The weight change rate from the initial value is greater than minus 10%, and weather resistance is insufficient.

[0091] [Disintegrability] Measurement method Each of the coated granular fertilizers obtained in the Examples and Comparative Examples was placed in water to allow the fertilizer components to elute, and then dried for 30 days in a forced air dryer set at 45° C. 25 particles of each of the obtained hollow coated particles were placed in sea sand (20 to 35 mesh) being stirred at 300 rpm, and the particles were recovered after 5 minutes, and the disintegration rate was calculated using the above-mentioned formula (1).

[0092] Evaluation The disintegrability was evaluated based on the calculated disintegration rate according to the following criteria. The disintegration rate (%) and the evaluation of disintegrability are shown in Table 4.

[0093] ◎: The disintegration rate is 100% to 20% or more, and the disintegration property is particularly excellent. ○: The disintegration rate is less than 20% to 1% or more, and the disintegration property is excellent. ×: The disintegration rate is less than 1%, and the disintegration property is not good.

[0094] [Elution Rate] Measurement Method: 10 g of the coated granular fertilizer of each Example and Comparative Example and 200 ml of distilled water previously adjusted to 25°C were added to a 250 ml plastic container with a lid, and the container was allowed to stand in an incubator set to 25°C. On the 28th day, all the water was removed from the container, and the amount of urea contained in the removed water (urea elution amount) was determined by quantitative analysis (dimethylaminobenzaldehyde method, "Detailed Explanation of Fertilizer Analysis Methods, Second Revised Edition," edited by Koshino Masayoshi, 1988, Yokendo), and this was taken as the amount of eluted urea. Separately, the urea content in the same lot of coated granular fertilizer was also measured in advance using the dimethylbenzaldehyde method. The elution rate was calculated using the above-mentioned formula (3).

[0095] Evaluation The elution controllability of the fertilizer components was evaluated based on the calculated elution rate according to the following criteria. The elution rate (%) and the evaluation of elution controllability are shown in Table 4.

[0096] ◎: The dissolution rate is less than 10%, and the dissolution controllability is particularly excellent. ○: The dissolution rate is less than 80% to 10% or more, and the dissolution controllability is excellent. ×: The dissolution rate is 80% or more, and the dissolution controllability is insufficient.

[0097] [Overall Evaluation] The weather resistance, disintegration property, and elution controllability of the Examples and Comparative Examples were comprehensively evaluated as follows. The results are shown in Table 4. Note that for Comparative Example 6, no coated granular fertilizer was obtained and therefore no evaluation was performed, and therefore the result is indicated as "-" in the table.

[0098] ◎: Weather resistance is rated as ◯, and both disintegration property and dissolution controllability are rated as ◎, and are particularly excellent. ○: Weather resistance is rated as ◯, and either disintegration property or dissolution controllability is rated as ◯, and are excellent. ×: Either weather resistance, disintegration property, or dissolution controllability is rated as ×, and are insufficient.

[0099]

[0100] 1. Jet tower 2. Spray nozzle 3. Granular fertilizer (core material) 4. Circulating air flow piping 5. Coating mixture supply piping 6. Solid-gas separator 7. Condenser 8. Blower 9. Coating mixture preparation tank (dissolver) 10. Liquid transfer pump 11. Rectifier 12. Heater 13. Granular fertilizer outlet 14. Guide pipe 15. Granular fertilizer inlet 21. Restrictor disc 22. Main disc body 23. Spout hole

Claims

1. A coated granular fertilizer comprising a granular fertilizer and a coating covering the surface of the granular fertilizer, wherein the coating contains at least one α-olefin copolymer (A) selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C), and the α-olefin copolymer (A) satisfies the following (I): (I) a density of 0.911 to 0.935 (g / cm) measured by a method conforming to JIS K 6922-2 ３ ) 2. The coated granular fertilizer according to claim 1, wherein the α-olefin copolymer (A) is linear low-density polyethylene (LLDPE).

3. The coated granular fertilizer according to claim 1, wherein the α-olefin copolymer (A) has a weight average molecular weight of 20,000 to 150,000 as measured by GPC.

4. The coated granular fertilizer according to claim 1, wherein the hydrocarbon wax (B) has an acid value of less than 0.1 as measured by a method conforming to JIS K0070.

5. The coated granular fertilizer according to claim 1, wherein the hydrocarbon wax (B) has a contact angle with water of 90 to 110° in the sessile drop method of testing the wettability of a glass substrate surface according to JIS R3257.

6. The coated granular fertilizer according to claim 1, wherein the hydrocarbon wax (B) is a saturated hydrocarbon.

7. The coated granular fertilizer according to claim 1, wherein the hydrocarbon wax (B) has a weight average molecular weight of 500 to 3,000 as measured by GPC.

8. The coated granular fertilizer according to claim 1, wherein the filler (C) is at least one selected from the group consisting of talc, clay, and mica.

9. The coated granular fertilizer according to claim 1, wherein the coating accounts for 1 to 20 mass % of 100 mass % of the coated granular fertilizer.

10. The coated granular fertilizer according to claim 1, wherein the α-olefin copolymer (A) is contained in an amount of 10.0 to 50.0 mass % relative to 100 mass % of the coating.

11. The coated granular fertilizer according to claim 1, wherein the mass ratio (A / B) of the α-olefin copolymer (A) to the hydrocarbon wax (B) is 0.5 to 5.

0.

12. A method for producing a coated granular fertilizer according to any one of claims 1 to 11, comprising: a step (I) of preparing a dispersion containing an α-olefin copolymer (A) including at least one selected from the group consisting of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), a hydrocarbon wax (B) having a melting point of 80°C or higher, and a filler (C); and a step (II) of, after the step (I), supplying the dispersion in a spray form to the granular fertilizer in a fluidized state in a spouted tower type or fluidized bed type apparatus, thereby forming a coating on the surface of the granular fertilizer.

Images