Manufacturing method of coated granular fertilizer and coated granular fertilizer

Abstract

Provided are a method for manufacturing a coated granular fertilizer that has high homogeneity in a resin coating, and this coated granular fertilizer. The method for manufacturing a coated granular fertilizer that is composed of a granular fertilizer and a urethane resin coating film coating the granular fertilizer, said method comprising a step for adding a polyisocyanate component, a polyol component and diazabicyclononene to the granular fertilizer in a rotated state, and a step for performing polyaddition of the polyisocyanate component and the polyol component while maintaining the granular fertilizer in the rotated state to thereby form the urethane resin coating film on the surface of the granular fertilizer; and the coated granular fertilizer that has high homogeneity in the resin coating.

Description

[Technical Field]

[0001] This patent application claims priority under the Paris Convention to and the benefit of Japanese Patent Application No. 2020-206637 (filed December 14, 2020), the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a method for producing a coated granular fertilizer and a coated granular fertilizer. [Background technology]

[0003] Due to the aging of agricultural workers, the decline in the number of agricultural workers, and the increase in part-time farmers, various types of coated fertilizers with controlled release properties have been proposed as labor-saving fertilizers, capable of releasing fertilizer components at a predetermined time in accordance with plant growth. Previously, methods were known in which granular fertilizers were coated and encapsulated with resin, wax, or sulfur to control the release rate of fertilizer components. Another known method for producing resin-coated granular fertilizers involves adding uncured urethane containing a catalyst to tumbling granular fertilizers to coat the surfaces of the granular fertilizers with urethane resin (see, for example, Patent Document 1). However, these methods often result in adhesion between granular fertilizer particles or adhesion to the tumbling device, and therefore the coating uniformity and production efficiency of the resin-coated granular fertilizers were not necessarily satisfactory. To address these issues, a method for producing coated granular fertilizers was proposed in which liquid paraffin or the like is added to the surface of urea granules before resin coating to suppress particle aggregation and adhesion to the tumbling device (see Patent Document 2). However, even with this method, there is still room for improvement in terms of suppressing the occurrence of aggregation between particles and adhesion of particles to the rolling device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-202683 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-16685 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for producing a coated granular fertilizer having an excellent uniformity of resin coating. [Means for solving the problem]

[0006] The present inventors have conducted research to find an excellent method for producing resin-coated granular fertilizer, and as a result have found that by using diazabicyclononene as a catalyst in forming a coating in a method for producing a coated granular fertilizer, a coated granular fertilizer can be obtained in which the occurrence of aggregation between particles and adhesion of particles to a rolling device is suppressed, and have thus completed the present invention. That is, the present invention is as follows. [1] A method for producing a coated granular fertilizer comprising a granular fertilizer and a urethane resin coating that coats the granular fertilizer, A method for producing a coated granular fertilizer, comprising: a step of adding a polyisocyanate component, a polyol component, and diazabicyclononene to the granular fertilizer in a rolling state; and a step of polyadding the polyisocyanate component and the polyol component while maintaining the rolling state of the granular fertilizer, thereby forming the urethane resin coating on the surface of the granular fertilizer. [2] The method according to [1], wherein the amount of diazabicyclononene added is 0.01 to 2% by weight based on the total amount of the polyisocyanate component and the polyol component. [3] The method according to [1] or [2], comprising the following steps: (a) mixing a polyisocyanate component, a polyol component, and diazabicyclononene to obtain a mixture; (b) adding the mixture obtained in step (a) to the granular fertilizer in a rolling state; and (c) A step of maintaining the granular fertilizer in a rolling state and polymerizing the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer. [4] The method according to [1] or [2], comprising the following steps: (a) mixing a polyisocyanate component and a polyol component to obtain a mixture; (b) adding the mixture obtained in step (a) and diazabicyclononene separately to the granular fertilizer in a rolling state; and (c) A step of maintaining the granular fertilizer in a rolling state and polymerizing the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer. [5] The method according to [1] or [2], comprising the following steps: (a) mixing a polyol component and diazabicyclononene to obtain a mixture; (b) separately adding the polyisocyanate component and the mixture obtained in step (a) to the tumbling granular fertilizer; and (c) A step of maintaining the granular fertilizer in a rolling state and polymerizing the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer. [6] The method according to [1] or [2], comprising the following steps: (a) separately adding a polyisocyanate component, a polyol component, and diazabicyclononene to a granular fertilizer in a tumbling state; and (b) A step of maintaining the granular fertilizer in a rolling state and polyadding the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer. [7] The method according to any one of [1] to [6], wherein the polyisocyanate component contains an aromatic polyisocyanate. [8] The method according to any one of [1] to [7], wherein the polyol component contains a castor oil-modified diol. [9] The method according to any one of [1] to [7], wherein the polyol component contains two or more compounds selected from the group consisting of castor oil-modified diol, alkylene diol having 2 to 8 carbon atoms, and compounds having three or more hydroxyl groups.

[10] The method according to any one of [1] to [8], wherein the polyol component comprises a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a compound having three or more hydroxyl groups.

[11] A method for producing a granular fertilizer, comprising: The coated granular fertilizer (hereinafter referred to as "the coated granular fertilizer of the present invention"), wherein the resin coating contains a urethane resin which is a polyaddition product of a polyisocyanate component and a polyol component, and diazabicyclononene. [Effects of the Invention]

[0007] According to the present invention, the occurrence of aggregation between particles and adhesion of particles to the rolling device when resin coating the granular fertilizer is suppressed, and a resin coating can be applied more uniformly to each particle, thereby providing a coated granular fertilizer in which the variation in the elution pattern of each particle is suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0008] The method for producing a coated granular fertilizer of the present invention (hereinafter referred to as "the production method of the present invention") includes the steps of adding a polyisocyanate component, a polyol component, and diazabicyclononene to the surface of the granular fertilizer in a tumbling state; and polyadding the polyisocyanate component and the polyol component while maintaining the tumbling state of the granular fertilizer to form a urethane resin coating on the surface of the granular fertilizer.

[0009] The granular fertilizer used in the present invention may be a granular material containing fertilizer components. Furthermore, the granular fertilizer used in the present invention may be, for example, a granular material in which the fertilizer components are granulated alone, or a granular material containing the fertilizer components and a carrier that holds the fertilizer components.

[0010] In the present invention, the fertilizer components are not particularly limited and can be appropriately selected depending on the application and intended use of the coated granular fertilizer. Examples of fertilizer components include nitrogenous fertilizer components such as urea, ammonium nitrate, magnesium ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, sodium nitrate, calcium nitrate, potassium nitrate, lime nitrogen, formaldehyde-modified urea (UF), acetaldehyde-modified urea (CDU), isobutyraldehyde-modified urea (IBDU), and guanylurea (GU); phosphateous fertilizer components such as calcium superphosphate, calcium triple superphosphate, fused phosphorus, humic acid phosphorus, calcined phosphorus, calcined phosphorus, magnesium superphosphate, ammonium polyphosphate, potassium metaphosphate, calcium metaphosphate, magnesium phosphate, ammonium phosphate sulfate, potassium ammonium phosphate nitrate, and ammonium chloride phosphate; and potassium fertilizer components such as potassium chloride, potassium sulfate, potassium sodium sulfate, potassium magnesium sulfate, potassium bicarbonate, and potassium phosphate. These fertilizer components may be used alone or in combination of two or more.

[0011] In the present invention, the carrier for holding the fertilizer components can be appropriately selected depending on the type of fertilizer component, the application and purpose of the coated granular fertilizer, etc. The carrier may contain, for example, minerals such as kaolin minerals such as kaolinite, montmorillonite, smectite, talc, rosestone, silica, zeolite, and acid clay; vegetable matter such as cellulose, rice husk, starch, and soybean flour; and water-soluble substances such as lactose, sucrose, dextrin, salt, and sodium tripolyphosphate. The carrier may contain one or more of these components. Furthermore, the granular fertilizer may contain one type of carrier, or two or more types of carriers.

[0012] In the present invention, the granular fertilizer may further contain other components in addition to the fertilizer components and the carrier.

[0013] The granular fertilizer used in the present invention can be produced, for example, by a method of granulating the fertilizer components alone, or by a method of mixing the fertilizer components with a carrier (and optionally other components) and granulating them. The granulation method may be a conventional granulation method. Examples of such granulation methods include extrusion granulation, fluidized bed granulation, tumbling granulation, compression granulation, pan granulation, coating granulation, and adsorption granulation.

[0014] The particle size of the granular fertilizer used in the present invention is not particularly limited and can be appropriately selected depending on the types of fertilizer components and carriers, the application and purpose of the coated granular fertilizer, and the like. For example, the average particle size of the granular fertilizer may be 0.1 to 15 mm, 1 to 10 mm, or 1 to 5 mm. In this embodiment, for example, after obtaining a granular fertilizer by the above-mentioned production method, a granular fertilizer having any particle size can be obtained by classifying the granular fertilizer using a sieve with an appropriate opening size. In this specification, the average particle size of the granular fertilizer is defined as the arithmetic mean value (also referred to as the arithmetic mean value) of the diameter of a circle equivalent to the projected area, and is measured by a microscopic method (e.g., an electron microscope or an optical microscope). The measurement method may vary depending on the particle size of the granular fertilizer to be measured, and the like.

[0015] The shape of the granular fertilizer used in the present invention is not particularly limited and can be appropriately selected depending on the types of fertilizer components and carriers, the application and purpose of the resin-coated granular fertilizer, etc. The shape of the granular fertilizer may be, for example, spherical, polyhedral, cylindrical, or irregular, and is preferably close to spherical.

[0016] The diazabicyclononene used in the present invention is also called 1,5-diazabicyclo(4.3.0)nonene-5 or DBN, and is represented by the following structural formula (I). [ka]

[0017] An example of the diazabicyclononene used in the present invention is DBN (manufactured by San-Apro Co., Ltd.). In this production method, the diazabicyclononene may be used in a catalytic amount relative to the total amount of the polyisocyanate component and the polyol component, preferably in a proportion of 0.01 to 2% by weight, more preferably 0.01 to 1% by weight, and even more preferably 0.02 to 0.07% by weight.

[0018] In the present invention, urethane resin refers to a resin that has been three-dimensionally crosslinked by reacting a polyisocyanate component with a polyol component. In the present invention, a mixture of a polyisocyanate component and a polyol component (sometimes referred to as "uncured urethane") refers to a mixture in which the polyisocyanate component and the polyol component have not reacted at all, or in which a portion of the polyisocyanate component and the polyol component have reacted in advance to an extent that does not cause three-dimensional crosslinking. Such a mixture may be in the form of a solventless type, a solution type, an aqueous emulsion type, or the like, but a solventless type that is liquid when added to a granular fertilizer is preferably used.

[0019] In the present invention, the term "polyisocyanate" refers to a compound having two or more isocyanate groups. Examples of such polyisocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and derivatives thereof. In the present invention, from the viewpoint of sustained release performance (also referred to as slow release), the polyisocyanate preferably contains an aromatic polyisocyanate.

[0020] In the present invention, aromatic polyisocyanate refers to a compound having an aromatic ring and two or more isocyanate groups. The aromatic polyisocyanate may be a compound having one aromatic ring in the molecule, or a compound having multiple aromatic rings. The isocyanate group of the aromatic polyisocyanate is preferably directly bonded to the aromatic ring. The aromatic ring may be a benzene ring.

[0021] Specific examples of aromatic polyisocyanates include 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), tolidine diisocyanate (TODI), naphthalene-1,5-diisocyanate (NDI), tetramethylene xylylene diisocyanate (TMXDI), and polymethylene polyphenyl polyisocyanate (polymeric MDI), as well as derivatives thereof (e.g., modified isocyanurates, biurets, uretdiones, etc.). These aromatic polyisocyanates may be used alone or in combination of two or more.

[0022] From the viewpoint of sustained release performance, the aromatic polyisocyanate may be an aromatic polyisocyanate having two or more benzene rings each having an isocyanate group. In such an aromatic polyisocyanate, the number of isocyanate groups directly bonded to each benzene ring may be one or two or more. Examples of such aromatic polyisocyanates include MDI, TDI, TODI, and oligomers derived from these (e.g., polymeric MDI, etc.).

[0023] In the present invention, the term "aliphatic polyisocyanate" refers to a compound having an aliphatic chain and two or more isocyanate groups. Specific examples of such aliphatic polyisocyanates include hexamethylene diisocyanate (HDI), dimer diisocyanate (DDI), and norbornene diisocyanate (NBDI).

[0024] In the present invention, the alicyclic polyisocyanate refers to a compound having a non-aromatic saturated or unsaturated carbon ring and two or more isocyanate groups. Examples of such alicyclic polyisocyanates include isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), and hydrogenated XDI.

[0025] In the present invention, lysine triisocyanate, lysine diisocyanate, etc. can also be used as the polyisocyanate. Examples of polyisocyanate derivatives include modified products such as isocyanurates, biurets, and uretdiones.

[0026] When the polyisocyanate component contains an aromatic polyisocyanate, the proportion of the aromatic polyisocyanate in the polyisocyanate component may be 30% by weight or more, 50% by weight or more, or 100% by weight, from the viewpoint of sustained release performance.

[0027] In the present invention, the polyol component refers to a compound having two or more hydroxyl groups per molecule. Examples of such polyol components include alkylene diols having 2 to 8 carbon atoms, polyether polyols, polyester polyols, vegetable oils having two or more hydroxyl groups, and modified products thereof. In the present invention, polyether polyol refers to a compound having two or more ether bonds and two or more hydroxyl groups in the molecule. Polyether polyols can be obtained, for example, by polyaddition of ethylene oxide or propylene oxide using a polyhydric alcohol, amino alcohol, or amine as an initiator. A specific example of polyether polyol is polytetramethylene ether glycol obtained by polymerizing tetrahydrofuran. In the present invention, polyester polyol refers to a compound having two or more ester bonds and two or more hydroxyl groups in the molecule. Polyester polyols can be obtained, for example, by reacting a polyhydric alcohol, a polyether polyol, and a carboxylic acid-containing compound. Alternatively, they can be obtained, for example, by ring-opening polymerization of a cyclic ester compound using a polyhydric alcohol as an initiator.

[0028] Examples of vegetable oils having two or more hydroxyl groups include castor oil, soybean oil, and cottonseed oil. Examples of modified vegetable oils having two or more hydroxyl groups include castor oil-modified diols and castor oil-modified polyols having three or more hydroxyl groups. In the present invention, from the viewpoint of sustained release performance, it is preferable that the polyol component contains a castor oil-modified diol. Also, from the viewpoint of sustained release performance, it is more preferable that the polyol component contains two or more (i.e., two or three) compounds selected from the group consisting of a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a compound having three or more hydroxyl groups.

[0029] In the present invention, the term "castor oil-modified diol" refers to a compound that can be derived from castor oil by a chemical reaction and has two hydroxyl groups. The castor oil-modified diol may be derived from castor oil, or may be a compound that can be derived from castor oil but is produced from a raw material other than castor oil. Castor oil is a fatty oil whose main component is a glyceride of ricinoleic acid, and the castor oil-modified diol may be, for example, a ricinoleic acid-modified diol.

[0030] In the present invention, commercially available castor oil-modified diols can be used. Examples of such commercially available products include URIC H-62 (hydroxyl value: 245 to 275, manufactured by Ito Oil Mills, Ltd.), URIC Y-202 (hydroxyl value: 110 to 120, manufactured by Ito Oil Mills, Ltd.), URIC Y-403 (hydroxyl value: 150 to 170, manufactured by Ito Oil Mills, Ltd.), URIC Y-332 (hydroxyl value: 113 to 133, manufactured by Ito Oil Mills, Ltd.), URIC AC-005 (hydroxyl value: 194 to 214, manufactured by Ito Oil Mills, Ltd.), URIC AC-006 (hydroxyl value: 168 to 187, manufactured by Ito Oil Mills, Ltd.), URIC PH-5001 (hydroxyl value: 45, manufactured by Ito Oil Mills, Ltd.), URIC PH-5002 (hydroxyl value: 43, manufactured by Ito Oil Mills, Ltd.), and HS Examples of suitable hydroxyl groups include, but are not limited to, HS 2G-120 (hydroxyl value: 122, manufactured by Toyokuni Oil Mills Co., Ltd.), HS 2G-160R (hydroxyl value: 121, manufactured by Toyokuni Oil Mills Co., Ltd.), HS 2G-270B (hydroxyl value: 261, manufactured by Toyokuni Oil Mills Co., Ltd.), HS 2B-5500 (hydroxyl value: 178, manufactured by Toyokuni Oil Mills Co., Ltd.), and HS KA-001 (hydroxyl value: 224, manufactured by Toyokuni Oil Mills Co., Ltd.). Here, the "hydroxyl value" refers to the number of milligrams of potassium hydroxide corresponding to the hydroxyl groups in 1 g of sample, as defined in the Japanese Industrial Standards (JIS) Test Method for Polyethers for Polyurethanes (K 1557). In practice, this value is calculated by esterifying a test sample with a pyridine solution of phthalic anhydride and titrating the excess reagent with a sodium hydroxide solution.

[0031] When the polyol component contains a castor oil-modified diol, the content of the castor oil-modified diol in the polyol component may be 6% by weight or more, 8% by weight or more, 10% by weight or more, 30% by weight or more, 50% by weight or more, or 65% by weight or more, based on the total amount of the polyol component, from the viewpoint of sustained release performance. Also, the content of the castor oil-modified diol may be 93% by weight or less, 90% by weight or less, or 85% by weight or less, based on the total amount of the polyol component, from the viewpoint of sustained release performance.

[0032] In the present invention, from the viewpoint of sustained release performance, the polyol component may contain an alkylenediol having 2 to 8 carbon atoms (hereinafter also simply referred to as "alkylenediol"). The number of carbon atoms in the alkylenediol is preferably 3 or more, more preferably 4 or more, and preferably 7 or less, or more preferably 6 or less.

[0033] The alkylene diol may be linear or branched. Examples of linear alkylene diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,8-octanediol. Examples of branched alkylene diols include 2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, and 2,3-dimethyl-1,4-butanediol.

[0034] When the polyol component contains an alkylene diol, the content of the alkylene diol in the polyol component may be 4% by weight or more, 6% by weight or more, 8% by weight or more, or 10% by weight or more, based on the total amount of the polyol component, from the viewpoint of sustained release performance. Also, the content of the alkylene diol may be 25% by weight or less, 21% by weight or less, 20% by weight or less, 18% by weight or less, or 15% by weight or less, based on the total amount of the polyol component, from the viewpoint of sustained release performance.

[0035] In the present invention, from the viewpoint of sustained release performance, the polyol component may contain a compound having three or more hydroxyl groups. In the present invention, a compound having three or more hydroxyl groups means a compound having three or more hydroxyl groups per molecule. The number of hydroxyl groups per molecule of a compound having three or more hydroxyl groups may be 3 to 8, or 3 to 6.

[0036] Examples of compounds having three or more hydroxyl groups include polyether polyols having three or more hydroxyl groups, castor oil, castor oil-modified polyols having three or more hydroxyl groups (e.g., castor oil-modified triols), poly(meth)acrylic acid polyols having three or more hydroxyl groups, condensation polyester polyols having three or more hydroxyl groups, and lactone polyester polyols having three or more hydroxyl groups. One compound having three or more hydroxyl groups may be used alone, or two or more compounds may be used in combination. Commercially available compounds having three or more hydroxyl groups may also be used. From the viewpoint of sustained release performance, castor oil-modified polyols having three or more hydroxyl groups and polyether polyols having three or more hydroxyl groups are preferred as compounds having three or more hydroxyl groups.

[0037] When the polyol component contains a compound having three or more hydroxyl groups, the content of the compound having three or more hydroxyl groups in the polyol component may be 2% by weight or more, 3% by weight or more, or 8% by weight or more, based on the total amount of the polyol component, from the viewpoint of sustained release performance. The content of the compound having three or more hydroxyl groups may be 87% by weight or less, 80% by weight or less, 76% by weight or less, 60% by weight or less, 40% by weight or less, or 20% by weight or less, based on the total amount of the polyol component, from the viewpoint of sustained release performance.

[0038] In one embodiment, the polyol component may be a mixture of a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a compound having three or more hydroxyl groups. In this embodiment, the amount of the castor oil-modified diol relative to the total amount of the polyol component may be 7% by weight or more, preferably 10% by weight or more, or 30% by weight or more, 50% by weight or more, or 65% by weight or more, from the viewpoint of sustained release performance. The amount of the castor oil-modified diol may be 93% by weight or less, preferably 80% by weight or less, from the viewpoint of sustained release performance. In this embodiment, the amount of the alkylene diol having 2 to 8 carbon atoms relative to the total amount of the polyol components may be 4% by weight or more, 6% by weight or more, preferably 8% by weight or more, or 10% by weight or more, from the viewpoint of sustained release performance. The amount of the alkylene diol having 2 to 8 carbon atoms may be 25% by weight or less, 21% by weight or less, 20% by weight or less, 18% by weight or less, or preferably 15% by weight or less, from the viewpoint of sustained release performance. Furthermore, in this embodiment, the amount of the compound having three or more hydroxyl groups per molecule relative to the total amount of the polyol components may be 2% by weight or more, preferably 8% by weight or more, from the viewpoint of sustained release performance. The amount of the polyol having more than two hydroxyl groups per molecule may be 87% by weight or less, preferably 78% by weight or less, and may be 60% by weight or less, 40% by weight or less, or 20% by weight or less, from the viewpoint of sustained release performance.

[0039] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a polyether polyol. In the above embodiment, the contents of the aromatic polyisocyanate, the castor oil-modified diol, the alkylene diol having 2 to 8 carbon atoms, and the polyether polyol may be 30 to 60% by weight, 30 to 60% by weight, 3 to 10% by weight, or 2 to 20% by weight, respectively, relative to the total amount of the polyisocyanate component and the polyol component.

[0040] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a castor oil-modified polyol. In the above embodiment, the contents of the aromatic polyisocyanate, the castor oil-modified diol, the alkylene diol having 2 to 8 carbon atoms, and the castor oil-modified polyol may be 30 to 60% by weight, 5 to 60% by weight, 3 to 10% by weight, or 5 to 50% by weight, respectively, relative to the total amount of the polyisocyanate component and the polyol component.

[0041] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a polyether polyol and castor oil. In the above embodiment, the contents of the aromatic polyisocyanate, polyether polyol, and castor oil may be 30 to 60% by weight, 5 to 60% by weight, or 5 to 30% by weight, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0042] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a polyether polyol. In the above embodiment, the contents of the aromatic polyisocyanate and the polyether polyol may be 30 to 60% by weight, or 30 to 60% by weight, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0043] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a polyether diol and a polyether polyol. In the above embodiment, the contents of the aromatic polyisocyanate, polyether diol, and polyether polyol may be 30 to 60 wt%, 5 to 30 wt%, or 5 to 60 wt%, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0044] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aliphatic polyisocyanate and a polyol component containing a polyether diol and a polyether polyol. In the above embodiment, the contents of the aliphatic polyisocyanate, polyether diol, and polyether polyol may be 30 to 60 wt%, 5 to 30 wt%, or 5 to 60 wt%, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0045] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a castor oil-modified polyol. In the above embodiment, the contents of the aromatic polyisocyanate and the castor oil-modified polyol may be 20 to 70% by weight, or 20 to 70% by weight, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0046] In another embodiment, the urethane resin may be a polyaddition product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a castor oil-modified diliol. In the above embodiment, the contents of the aromatic polyisocyanate and the castor oil-modified diliol may be 20 to 70% by weight, or 20 to 70% by weight, respectively, based on the total amount of the polyisocyanate component and the polyol component.

[0047] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aromatic polyisocyanate, 30 to 60 parts by weight of a castor oil-modified diol, 3 to 10 parts by weight of an alkylene diol having 2 to 8 carbon atoms, and 2 to 20 parts by weight of a polyether polyol.

[0048] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aromatic polyisocyanate, 5 to 60 parts by weight of a castor oil-modified diol, 3 to 10 parts by weight of an alkylene diol having 2 to 8 carbon atoms, and 5 to 50 parts by weight of a castor oil-modified polyol.

[0049] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aromatic polyisocyanate, 5 to 60 parts by weight of a polyether polyol, and 5 to 30 parts by weight of castor oil.

[0050] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aromatic polyisocyanate and 30 to 60 parts by weight of a polyether polyol.

[0051] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aromatic polyisocyanate, 5 to 30 parts by weight of a polyether diol, and 5 to 60 parts by weight of a polyether polyol.

[0052] In another embodiment, the urethane resin may be a polyaddition product of 30 to 60 parts by weight of an aliphatic polyisocyanate, 5 to 30 parts by weight of a polyether diol, and 5 to 60 parts by weight of a polyether polyol.

[0053] The ratio M2 / M1 of the number of moles of hydroxyl groups in the polyol component M2 to the number of moles of isocyanate groups in the polyisocyanate component M1 is preferably 0.7 or more, more preferably 0.9 or more, and is preferably 1.7 or less, more preferably 1.5 or less. When the ratio M2 / M1 is within the above range, excellent sustained release performance tends to be obtained.

[0054] The coated granular fertilizer of the present invention may have a resin coating other than the urethane resin coating. In this case, the content of the urethane resin in the entire resin coating may be 80% by weight or more, 90% by weight or more, or even 100% by weight based on the total weight of the resin coating.

[0055] The amount of the urethane resin in the coated granular fertilizer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, per 100 parts by mass of the granular fertilizer, and is preferably 20 parts by mass or less, more preferably 16 parts by mass or less, per 100 parts by mass of the granular fertilizer.

[0056] In the method for producing a resin-coated granular fertilizer of the present invention, a polyisocyanate component, a polyol component, and diazabicyclononene are used. Examples of steps using these components include the steps shown below, and the method for producing a resin-coated granular fertilizer of the present invention can include these steps. The method may include a step (A-1) of mixing a polyisocyanate component, a polyol component, and diazabicyclononene to obtain a mixture, a step (A-2) of adding the mixture obtained in step A-1 to a granular fertilizer in a tumbling state, and a step (A-3) of maintaining the tumbling state of the granular fertilizer to polyaddition the polyisocyanate component and the polyol component, thereby forming a urethane resin coating on the surface of the granular fertilizer (hereinafter, steps A-1 to A-3 may be collectively referred to as "step A"). The process may include a step (B-1) of mixing a polyisocyanate component and a polyol component to obtain a mixture, a step (B-2) of separately adding the mixture obtained in step B-1 and diazabicyclononene to a granular fertilizer in a tumbling state, and a step (B-3) of maintaining the tumbling state of the granular fertilizer to polyaddition the polyisocyanate component and the polyol component, thereby forming a urethane resin coating on the surface of the granular fertilizer (hereinafter, steps B-1 to B-3 may be collectively referred to as "step B"). The process may include a step (C-1) of mixing a polyol component with diazabicyclononene to obtain a mixture, a step (C-2) of separately adding the mixture obtained in step C-1 and a polyisocyanate component to a granular fertilizer in a tumbling state, and a step (C-3) of maintaining the tumbling state of the granular fertilizer to polyaddition the polyisocyanate component and the polyol component, thereby forming a urethane resin coating on the surface of the granular fertilizer (hereinafter, steps C-1 to C-3 may be collectively referred to as "step C"). The process may include a step (D-1) of separately adding a polyisocyanate component, a polyol component, and diazabicyclononene to the granular fertilizer in a rolling state, and a step (D-2) of maintaining the rolling state of the granular fertilizer to polyaddition the polyisocyanate component and the polyol component to form a urethane resin coating on the surface of the granular fertilizer (hereinafter, steps D-1 and D-2 may be collectively referred to as "step D"). When the polyisocyanate component, polyol component, and diazabicyclononene are added separately, the order of addition may be any of the following: polyisocyanate component, polyol component, and diazabicyclononene; polyol component, polyisocyanate component, and diazabicyclononene; polyol component, diazabicyclononene, and polyisocyanate component; polyisocyanate component, diazabicyclononene, and polyol component; diazabicyclononene, polyisocyanate component, and polyol component; or diazabicyclononene, polyol component, and polyisocyanate component. The temperature at which step A is carried out is set appropriately depending on the types of polyisocyanate component and polyol component used, the size of the granular fertilizer, and the like, but the temperature inside the rotating tank in which the granular fertilizer is tumbling is usually in the range of 40 to 100° C., preferably in the range of 55 to 75° C. After the mixture of the polyisocyanate component, polyol component, and diazabicyclononene is added, the tumbling state of the granular fertilizer is maintained until the polyaddition of the polyisocyanate component and the polyol component progresses to harden the urethane and prevent adhesion between the resin-coated granules, and the time for maintaining the tumbling state is usually about 1 to 30 minutes, and from the viewpoint of production efficiency, preferably about 1 to 20 minutes. The temperature at which step B is carried out is set appropriately depending on the types of polyisocyanate component and polyol component used, the size of the granular fertilizer, and the like, but the temperature inside the rotating tank in which the granular fertilizer is tumbling is usually in the range of 40 to 100° C., preferably in the range of 55 to 75° C. After the mixture of the polyisocyanate component and the polyol component and the diazabicyclononene are added, the tumbling state of the granular fertilizer is maintained until the polyaddition of the polyisocyanate component and the polyol component progresses to harden the urethane and prevent adhesion between the resin-coated granules, and the time for maintaining the tumbling state is usually about 2 to 40 minutes, and from the viewpoint of production efficiency, preferably about 2 to 30 minutes. The temperature at which step C is carried out is appropriately set depending on the types of polyisocyanate component and polyol component used, the size of the granular fertilizer, etc., but the temperature inside the rotating tank in which the granular fertilizer is tumbling is usually in the range of 40 to 100° C., preferably in the range of 55 to 75° C. After the mixture of the polyol component and diazabicyclononene and the polyisocyanate component are added, the tumbling state of the granular fertilizer is maintained until the polyaddition of the polyisocyanate component and the polyol component progresses, the urethane hardens, and the resin-coated granules no longer adhere to each other; however, the time for maintaining the tumbling state is usually about 2 to 40 minutes, and from the viewpoint of production efficiency, about 2 to 30 minutes. The temperature at which step D is carried out is appropriately set depending on the types of polyisocyanate component and polyol component used, the size of the granular fertilizer, and the like, but the temperature inside the rotating tank in which the granular fertilizer is tumbling is usually in the range of 40 to 100° C., and preferably in the range of 55 to 75° C. After the addition of the polyisocyanate component, polyol component, and diazabicyclononene, the tumbling state of the granular fertilizer is maintained until polyaddition of the polyisocyanate component and the polyol component progresses to harden the urethane and prevent adhesion between the resin-coated granules. The time for maintaining the tumbling state is usually about 2 to 40 minutes, and from the viewpoint of production efficiency, about 2 to 30 minutes.

[0057] The coated granular fertilizer of the present invention can be produced by a production method including any one of the above steps A to D, but from the viewpoint of the homogeneity of the resin coating, step A is preferred.

[0058] In the method for producing a resin-coated granular fertilizer of the present invention, any one of the steps A to D may be carried out only once. Furthermore, any one of the steps A to D may be further repeated one or more times on the resin-coated granules obtained by any one of the steps A to D (hereinafter, this may be referred to as "step E"). Here, the additional steps A to D may be the same as or different from the previously carried out one or more times of steps A to D. The thickness of the resin coating can be adjusted by adjusting the number of times step E is carried out. Step E may be carried out immediately after the previous step while maintaining the tumbling state of the granular fertilizer. The polyisocyanate component and polyol component used in step E may be the same as or different from the polyisocyanate component and polyol component used in the previous step, but from the viewpoint of production efficiency, the same type of polyisocyanate component and polyol component are usually used.

[0059] The total amount of the polyol component and the polyisocyanate component used in the method for producing a resin-coated granular fertilizer of the present invention is appropriately set depending on the size and shape of the granular fertilizer used and the degree of elution control required for the resin-coated granular fertilizer to be produced, but the total amount of the polyol component and the polyisocyanate used in steps A to D and, optionally, step E, is usually about 2 to 30 parts by weight, and preferably about 4 to 18 parts by weight, per 100 parts by weight of the granular fertilizer.

[0060] The method for rolling the granular fertilizer is not particularly limited to a specific device, and a known, conventional device can be used. Examples of such devices include a concrete mixer and a drum mixer. Among the above devices, a device equipped with a heating system is preferably used because it allows for high precision in the manufacturing method of the present invention and adjustment of the processing time.

[0061] The coated granular fertilizer of the present invention may further contain a resin coating other than the resin coating containing diazabicyclononene and a urethane resin which is a polyadduct of a polyisocyanate component and a polyol component. Examples of such a resin coating include a coating containing a urethane resin which is a polyadduct of any polyisocyanate component and any polyol component, but not containing diazabicyclononene. The resin coating may further contain components other than the urethane resin and diazabicyclononene. For example, it may contain solvents such as organic solvents and water, which may be solvents used in the production of the urethane resin. The resin coating may also contain pigments, dyes, antibacterial agents, preservatives, plasticizers, decomposition accelerators, and the aforementioned carriers, depending on the purpose.

[0062] The coated granular fertilizer of the present invention may further contain other components (for example, anti-floating agents, anti-caking agents, active agricultural chemical ingredients, waxes, etc.) in addition to the granular fertilizer and the resin coating.

[0063] The coated granular fertilizer of the present invention may further contain a hydrophobic liquid compound having a boiling point of 100°C or higher (hereinafter also referred to as "the present hydrophobic liquid compound"). In the present invention, the present hydrophobic liquid compound means a compound that has fluidity at 20°C and has a water solubility of 10 ppm or less at 20°C. The present hydrophobic liquid compound may be contained in the granular fertilizer, or may be present as a coating that coats the granular fertilizer. When the present hydrophobic liquid compound is present as a coating, the coating may be formed directly on the surface of the granular fertilizer, or may be formed on a resin coating that coats the granular fertilizer.

[0064] The hydrophobic compound is blended, for example, when producing a resin-coated granular fertilizer using an apparatus for tumbling the granular fertilizer. Examples of the hydrophobic compound include aliphatic hydrocarbons such as liquid paraffin, and aromatic hydrocarbons such as phenylxylylethane and alkylbenzene (specifically, Solvesso 150, manufactured by ExxonMobil Chemical). The content of the hydrophobic liquid compound in the resin-coated granular fertilizer may be 0.1 to 5 parts by mass per 100 parts by mass of the granular fertilizer.

[0065] The resin coating may be formed directly on the surface of the granular fertilizer. When a coating other than the resin coating (for example, a coating of the above-mentioned hydrophobic liquid compound) is formed on the surface of the granular fertilizer, the resin coating may be formed on the other coating.

[0066] The resin coating may be formed so as to cover the entire surface of the granular fertilizer, or may be formed so as to cover a part of the surface of the granular fertilizer.

[0067] The thickness of the resin coating can be appropriately selected depending on the application and purpose of the resin-coated granular fertilizer. The thickness of the resin coating may be, for example, 8 μm or more, preferably 10 μm or more. The thickness of the resin coating may be, for example, 400 μm or less, preferably 200 μm or less. According to an embodiment, the thickness of the resin coating is 8 μm or more and 4200 μm or less, 8 μm or more and 200 μm or less, 10 μm or more and 400 μm or less, or 10 μm or more and 200 μm or less. In this specification, the thickness of the resin coating refers to a value measured by observing the cross section of the resin-coated granular fertilizer with a scanning electron microscope (SEM). The thickness of the resin coating can also be expressed, for example, as the average value of thickness measurements at 10 locations. By adjusting the thickness of the resin coating, it is possible to adjust, for example, the amount of fertilizer components eluted and the shape of the elution curve.

[0068] The particle size of the coated granular fertilizer can be appropriately selected depending on the application and purpose of use of the coated granular fertilizer. For example, the average particle size of the coated granular fertilizer may be 0.1 to 15 mm, or 1 to 5 mm. In this specification, the average particle size of the coated granular fertilizer is defined as the arithmetic mean value of the diameter of a circle equivalent to the projected area, and is measured by a microscope or the like. [Example]

[0069] The present invention will now be described in more detail with reference to examples such as production examples, but the present invention is not limited to these examples.

[0070] Manufacturing Example 1 Castor oil-modified diol (manufactured by Ito Oil Mills, trade name: URIC H-62, number of hydroxyl groups per molecule: 2, hydroxyl value: 274), castor oil-modified polyol (manufactured by Ito Oil Mills, trade name: URIC H-73X, number of hydroxyl groups per molecule: 3, hydroxyl value: 270), and 1,4-butanediol (manufactured by BASF Idemitsu Co., Ltd., trade name: 1,4-BDO) were mixed at room temperature in a weight ratio of 67.8:20.8:11.4 to obtain polyol mixture A. Subsequently, 2677.08 g of the obtained polyol mixture A and 2.50 g of diazabicyclononene (San-Apro Co., Ltd., trade name: DBN) were mixed at room temperature to obtain polyol mixture I. 50,000 g of granular urea (large granular urea, particle size approximately 3 mm, spherical, approximately 60 particles per 1 g) was charged into a concrete mixer and allowed to tumble. The granular urea in the tumbled state was heated to approximately 66°C by applying hot air from a hot air generator, and then mixed with liquid paraffin (manufactured by Matsumura Oil Research Institute, trade name: Moresco White P-350P, kinematic viscosity at 37.78°C: 76 mmHg). 2 500 g of (Isocyanate / S) was added, and the rolling state was maintained for 3 minutes. Next, 267.96 g of the polyol mixture I heated to 50°C and 232.29 g of aromatic diisocyanate (manufactured by Sumika Bayer Urethane, trade name: SBU Isocyanate J243) heated to 50°C were quickly stirred and mixed to obtain a mixture, which was then added to the rolling granular urea, and the rolling state was maintained for 7 minutes or more while hot air from a hot air generator was applied. The above operations (stirring and mixing of polyol mixture I and aromatic diisocyanate, adding the mixture to the rolling granular urea, and maintaining the rolling state) were repeated until the total amount of the mixture of polyol mixture I and aromatic diisocyanate added reached 5,002.5 g, thereby obtaining a coated granular fertilizer of the present invention. In the above manufacturing process, no significant aggregation of the granules or adhesion of the granules to the inner wall of the concrete mixer was observed, and the granules rolled smoothly inside the concrete mixer. Furthermore, when the coated granular fertilizer obtained by the above manufacturing process was visually observed, the coating state was found to be uniform.

[0071] Manufacturing Example 2 50,000 g of granular urea (large granular urea, particle size approximately 3 mm, spherical, approximately 60 particles per 1 g) was charged into a concrete mixer and allowed to tumble. The granular urea in the tumbled state was heated to approximately 66°C by applying hot air from a hot air generator, and then mixed with liquid paraffin (manufactured by Matsumura Oil Research Institute, trade name: Moresco White P-350P, kinematic viscosity at 37.78°C: 76 mmHg). 2 500 g of polyol mixture I (174.22 g of aromatic diisocyanate (manufactured by Sumika Bayer Urethane, trade name: SBU Isocyanate J243)) was added and the rolling state was continued for 3 minutes. Next, 200.97 g of the polyol mixture I heated to 50°C and 174.22 g of aromatic diisocyanate heated to 50°C were quickly stirred and mixed, and the resulting mixture was added to the rolling granular urea, and the rolling state was maintained for 6 minutes or more while hot air from a hot air generator was applied. The above operations (stirring and mixing of polyol mixture I and aromatic diisocyanate, adding the mixture to the rolling granular urea, and maintaining the rolling state) were repeated until the total amount of the mixture of polyol mixture I and aromatic diisocyanate added reached 4,877.47 g, thereby obtaining a coated granular fertilizer of the present invention. Throughout the above manufacturing process, no significant aggregation of the granules or adhesion of the granules to the inner wall of the concrete mixer was observed, and the granules rolled smoothly inside the concrete mixer. Furthermore, when the coated granular fertilizer obtained by the above manufacturing process was visually observed, the coating state was found to be uniform.

[0072] Manufacturing Example 3 Polyol mixture A2677.08 g and 3.50 g of diazabicyclononene (San-Apro Co., Ltd., trade name: DBN) were mixed at room temperature to obtain polyol mixture II. 50,000 g of granular urea (large granular urea, particle size approximately 3 mm, spherical, approximately 60 particles per 1 g) was charged into a concrete mixer and allowed to tumble. The granular urea in the tumbled state was heated to approximately 66°C by applying hot air from a hot air generator, and then mixed with liquid paraffin (manufactured by Matsumura Oil Research Institute, trade name: Moresco White P-350P, kinematic viscosity at 37.78°C: 76 mmHg). 2500 g of polyol mixture II (polyol mixture II / S) was added, and the rolling state was continued for 3 minutes. Next, 268.06 g of the polyol mixture II heated to 50°C and 232.29 g of aromatic diisocyanate (manufactured by Sumika Bayer Urethane, trade name: SBU Isocyanate J243) heated to 50°C were quickly stirred and mixed to obtain a mixture, which was then added to the rolling granular urea, and the rolling state was maintained for 7 minutes or more while hot air from a hot air generator was applied. The above operations (stirring and mixing of polyol mixture II and aromatic diisocyanate, addition of the mixture to the rolling granular urea, and maintaining the rolling state) were repeated until the total amount of the mixture of polyol mixture II and aromatic diisocyanate added reached 5,003.5 g, thereby obtaining a coated granular fertilizer of the present invention. Throughout the above manufacturing process, no significant aggregation of the granules or adhesion of the granules to the inner wall of the concrete mixer was observed, and the granules rolled smoothly inside the concrete mixer. Furthermore, when the coated granular fertilizer obtained by the above manufacturing process was visually observed, the coating state was found to be uniform.

[0073] Comparative Manufacturing Example 1 50,000 g of granular urea (large granular urea, particle size approximately 3 mm, spherical, approximately 60 particles per 1 g) was charged into a concrete mixer and allowed to tumble. The granular urea in the tumbled state was heated to approximately 66°C by applying hot air from a hot air generator, and then mixed with liquid paraffin (manufactured by Matsumura Oil Research Institute, trade name: Moresco White P-350P, kinematic viscosity at 37.78°C: 76 mmHg). 2 500 g of polyol mixture A (267.71 g) was added, and the rolling state was continued for 3 minutes. Next, 267.71 g of the polyol mixture A heated to 50°C and 232.29 g of aromatic diisocyanate (manufactured by Sumika Bayer Urethane, trade name: SBU Isocyanate J243) heated to 50°C were quickly stirred and mixed to obtain a mixture, which was then added to the rolling granular urea, and the rolling state was maintained for 9 minutes or more while hot air from a hot air generator was applied. The above operations (stirring and mixing of polyol mixture A and aromatic diisocyanate, addition of the mixture to the rolling granular urea, and maintaining the rolling state) were repeated until the total amount of the mixture of polyol mixture A and aromatic diisocyanate added reached 5,000.0 g, thereby obtaining a comparative coated granular fertilizer. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer.

[0074] Comparative Manufacturing Example 2 Polyol mixture III was obtained by mixing 2677.08 g of polyol mixture A and 2.50 g of an ethyleneamine derivative (manufactured by Tosoh Corporation, trade name: TOYOCAT-DB30) at room temperature. A comparative coated granular fertilizer was obtained in the same manner as in Production Example 1, except that Polyol Mixture III was used instead of Polyol Mixture I. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer.

[0075] Comparative Manufacturing Example 3 Polyol mixture IV was obtained by mixing 2677.08 g of polyol mixture A and 2.50 g of 1,8-diazabicyclo(5.4.0)undecene-7 (Sanapro Co., Ltd., trade name: DBU (registered trademark)) at room temperature. A comparative coated granular fertilizer was obtained in the same manner as in Production Example 1, except that Polyol Mixture IV was used instead of Polyol Mixture I. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer.

[0076] Comparative Manufacturing Example 4 Polyol mixture V was obtained by mixing 2677.08 g of polyol mixture A and 3.50 g of 1,8-diazabicyclo(5.4.0)undecene-7 (Sanapro Co., Ltd., trade name: DBU (registered trademark)) at room temperature. A comparative coated granular fertilizer was obtained in the same manner as in Production Example 3, except that Polyol Mixture V was used instead of Polyol Mixture II. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer.

[0077] Comparative Manufacturing Example 5 Polyol mixture VI was obtained by mixing 2677.08 g of polyol mixture A and 2.50 g of phenol salt of 1,8-diazabicyclo(5,4,0)undecene-7 (Sanapro Co., Ltd., trade name: U-CAT (registered trademark) SA-1) at room temperature. A comparative coated granular fertilizer was obtained in the same manner as in Production Example 1, except that polyol mixture VI was used instead of polyol mixture I. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer.

[0078] Comparative Manufacturing Example 6 2677.08 g of polyol mixture A and 25.0 g of 2,4,6-tris(dimethylaminomethyl)phenol (Kayaku Akzo Co., Ltd., trade name: TAP) were mixed at room temperature to obtain polyol mixture VII. 50,000 g of granular urea (large granular urea, particle size approximately 3 mm, spherical, approximately 60 particles per 1 g) was charged into a concrete mixer and allowed to tumble. The granular urea in the tumbled state was heated to approximately 66°C by applying hot air from a hot air generator, and then mixed with liquid paraffin (manufactured by Matsumura Oil Research Institute, trade name: Moresco White P-350P, kinematic viscosity at 37.78°C: 76 mmHg). 2 500 g of polyol mixture VII (Vol VII / S) was added, and the rolling state was continued for 3 minutes. Next, 270.21 g of the polyol mixture VII heated to 50°C and 232.29 g of aromatic diisocyanate (manufactured by Sumika Bayer Urethane, trade name: SBU Isocyanate J243) heated to 50°C were quickly stirred and mixed to obtain a mixture, which was then added to the rolling granular urea, and the rolling state was maintained for 10 minutes or more while hot air from a hot air generator was applied. The above operations (stirring and mixing of polyol mixture VII and aromatic diisocyanate, addition of the mixture to the rolling granular urea, and maintaining the rolling state) were repeated until the total amount of the mixture of polyol mixture VII and aromatic diisocyanate added reached 5,025.0 g, thereby obtaining a comparative coated granular fertilizer. In the above manufacturing process, clumps of granules were observed in some places, and the granules were not rolling properly inside the concrete mixer. [Industrial Applicability]

[0079] According to the method for producing a coated granular fertilizer of the present invention, it is possible to provide a coated granular fertilizer in which the occurrence of aggregation between particles and adhesion of particles to a rolling device is suppressed.

Claims

1. A method for producing a coated granular fertilizer comprising a granular fertilizer and a urethane resin coating that coats the granular fertilizer, A method for producing a coated granular fertilizer, comprising: a step of adding a polyisocyanate component, a polyol component, and diazabicyclononene to the granular fertilizer in a rolling state; and a step of polyadding the polyisocyanate component and the polyol component while maintaining the rolling state of the granular fertilizer, thereby forming the urethane resin coating on the surface of the granular fertilizer.

2. 2. The method according to claim 1, wherein the amount of diazabicyclononene added is 0.01 to 2% by weight based on the total amount of the polyisocyanate component and the polyol component.

3. 3. The method according to claim 1 or 2, comprising the steps of: (a) mixing a polyisocyanate component, a polyol component, and diazabicyclononene to obtain a mixture; (b) adding the mixture obtained in step (a) to the granular fertilizer in a rolling state; and (c) A step of maintaining the tumbling state of the granular fertilizer and polyadding the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer.

4. 3. The method according to claim 1 or 2, comprising the steps of: (a) mixing a polyisocyanate component and a polyol component to obtain a mixture; (b) adding the mixture obtained in step (a) and diazabicyclononene separately to the granular fertilizer in a rolling state; and (c) A step of maintaining the tumbling state of the granular fertilizer and polyadding the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer.

5. 3. The method according to claim 1 or 2, comprising the steps of: (a) mixing a polyol component and diazabicyclononene to obtain a mixture; (b) separately adding the polyisocyanate component and the mixture obtained in step (a) to the granular fertilizer in a tumbling state; and (c) A step of maintaining the tumbling state of the granular fertilizer and polyadding the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer.

6. 3. The method according to claim 1 or 2, comprising the steps of: (a) separately adding a polyisocyanate component, a polyol component, and diazabicyclononene to a granular fertilizer in a tumbling state; and (b) A step of maintaining the tumbling state of the granular fertilizer and polyadding the polyisocyanate component and the polyol component to form a resin coating on the surface of the granular fertilizer.

7. The method according to any one of claims 1 to 6, wherein the polyisocyanate component comprises an aromatic polyisocyanate.

8. The method according to any one of claims 1 to 7, wherein the polyol component comprises a castor oil-modified diol.

9. The method according to any one of claims 1 to 7, wherein the polyol component comprises two or more compounds selected from the group consisting of castor oil-modified diols, alkylene diols having 2 to 8 carbon atoms, and compounds having three or more hydroxyl groups.

10. The method according to any one of claims 1 to 8, wherein the polyol component comprises a castor oil-modified diol, an alkylene diol having 2 to 8 carbon atoms, and a compound having three or more hydroxyl groups.

11. The present invention provides a granular fertilizer and a resin coating that coats the granular fertilizer, The coated granular fertilizer, wherein the resin coating contains a urethane resin which is a polyaddition product of a polyisocyanate component and a polyol component, and diazabicyclononene.

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