JP2006298673A - Polyurethane-coated granular fertilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated granular fertilizer excellent in initial elution preventing effect of fertilizer components and coated with a polyurethane resin. <P>SOLUTION: The coated granular fertilizer is a fertilizer coated with the polyurethane resin obtained by the reaction of a polyol containing a polyol (1) in which the ratio (the number of carbon atoms)/(the number of oxygen atoms) is ≤3.0 and a polyol (2) in which the ratio (the number of carbon atoms)/(the number of oxygen atoms) is ≥5.0 in a ratio satisfying the following calculation formula with an isocyanate. Where, the calculation formula is [(the weight of polyol (1))×(the hydroxyl value of the polyol (1))]/[(the weight of polyol (2))×(the hydroxyl value of the polyol (2))]=2.4-6.0. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a coated granular fertilizer coated with a polyurethane resin obtained by reacting a polyol containing two types of polyols having different properties in a specific ratio with an isocyanate.

Conventionally, many coated granular fertilizers in which granular fertilizer is coated with a resin such as polyurethane resin are known for the purpose of slow release of the fertilizer from the viewpoint of labor saving of farm work and the like. In addition, a method of combining different hydrophobic substances such as waxes is also known when a known polyurethane resin alone is not sufficient to suppress initial elution (for example, Patent Document 1).

JP 2003-246692 A

An object of the present invention is to provide a coated granular fertilizer coated with a polyurethane resin having an excellent effect of suppressing the initial elution of fertilizer components.

As a result of intensive studies on the polyurethane resin excellent in the initial elution suppression effect of the fertilizer component, the present inventor used two types of polyols having different properties in a specific ratio in the polyol as a raw material of the polyurethane resin. The present inventors have found that a polyurethane resin having an excellent initial elution suppression effect can be obtained, and completed the present invention.
That is, the present invention is [Invention 1].
A polyol (1) having a ratio of carbon atoms / oxygen atoms in the molecule of 3.0 or less and a polyol (2) having a ratio of carbon atoms / oxygen atoms in the molecule of 5.0 or more are shown below. A polyol containing a ratio satisfying the calculation formula;
Coated granular fertilizer coated with polyurethane resin obtained by reacting with isocyanate:
[Weight of polyol (1) x hydroxyl value of polyol (1)]
/ [Weight of polyol (2) × hydroxyl value of polyol (2)] = 2.4 to 6.0;
[Invention 2]
A polyol (1) having a ratio of carbon atoms / oxygen atoms in the molecule of 3.0 or less and a polyol (2) having a ratio of carbon atoms / oxygen atoms in the molecule of 5.0 or more are shown below. A polyol containing a ratio satisfying the calculation formula;
Coated granular fertilizer coated with polyurethane resin obtained by reacting with isocyanate:
[Weight of polyol (1) x hydroxyl value of polyol (1)]
/ [Weight of polyol (2) × hydroxyl value of polyol (2)] = 2.4 to 4.8;
[Invention 3]
The coated granular fertilizer according to invention 1 or 2, wherein at least one of the polyol (1) and the polyol (2) is a trifunctional or higher functional polyol;
[Invention 4]
The coated granular fertilizer according to invention 1, 2, or 3, wherein the isocyanate is an aromatic isocyanate;
It is.

With the coated granular fertilizer of the present invention, a polyurethane resin-coated granular fertilizer excellent in sustained release of fertilizer components can be obtained.

In the present invention, the polyurethane resin means a polymer having a urethane bond [N—C (═O) —O] in the main chain of the polymer structure, and substantially includes an isocyanate group [NCO], a hydroxyl group [OH], and It is a resin that forms a polymer by the reaction of In the present invention, a polyol is a compound having a plurality of hydroxyl groups in the molecule that can react with an isocyanate group. Naturally, the polyol may contain an ether bond or an ester bond in the molecule. In the present invention, the isocyanate is a compound having the above isocyanate group in the molecule, and usually means a polyisocyanate having two or more isocyanate groups in the molecule. However, a compound having a urethane bond, a hydroxyl group and an isocyanate group, which is produced by reacting a polyisocyanate and a polyol, and a multimerized polyisocyanate are also included in the isocyanate in the present invention.

The polyol used in the coated granular fertilizer of the present invention contains two types of polyols having different properties. The two types of polyols differ in the ratio of the number of carbon atoms / oxygen atoms in the polyol molecule, one being a hydrophilic polyol and the other being a hydrophobic polyol.

The polyol (1), which is a relatively hydrophilic polyol, is a polyol having a ratio of carbon atoms / oxygen atoms in the molecule of 3.0 or less. The ratio between the number of carbon atoms and the number of oxygen atoms in the molecule can be actually measured from the elemental analysis value of the polyol, or can be calculated from the structure of the polyol. Examples of the polyol (1) include an ethylene oxide adduct and a propylene oxide adduct starting from a C2 to C6 low molecular polyol and a condensate of a low molecular polyol and polylactic acid. Examples of the low molecular polyol used in this case include diols such as ethylene glycol and 1,3-propanediol; triols such as glycerol and trimethylolpropane; tetraols such as pentaerythrol; polyols such as sucrose.
For example, the ratio of the number of carbon atoms / number of oxygen atoms of a polyol (composition formula: C ₂₁ H ₄₄ O ₉ ) in which 6 molecules of propylene oxide are added to glycerol is 2.33.

Polyol (2), which is a relatively hydrophobic polyol, is a polyol having a ratio of carbon atoms / oxygen atoms in the molecule of 5.0 or more. Examples of the polyol (2) include polyolefin polyols such as polybutadiene polyol and polyisoprene polyol; fatty acid ester polyols such as oleic acid monoglyceride, stearic acid monoglyceride, ricinoleic acid triglyceride and 12-oxyoctadecanoic acid triglyceride. .
For example, the ratio of the number of carbon atoms / the number of oxygen atoms of ricinoleic acid triglyceride (C ₅₇ H ₁₀₄ O ₉ ) is 6.33.
In the present invention, it is preferable that at least one of the polyol (1) and the polyol (2) is a tri- or higher functional polyol capable of forming a three-dimensional crosslinking.

The polyol used for the coated granular fertilizer of the present invention contains the above two different types of polyols in a specific ratio. That is, the ratio of the product of the weight of the hydrophilic polyol (1) and its hydroxyl value to the product of the weight of the hydrophobic polyol (2) and its hydroxyl value is 2.4 to 6.0, preferably 2 The range is from 4 to 4.8.
In the present invention, the hydroxyl value is a value indicating the content of hydroxyl group (OH) per unit weight of the substance, and is usually necessary for neutralizing acetic acid bound to an acetylated product obtained from 1 g of a sample. It is expressed in mg of potassium hydroxide (KOH). Specifically, it can be measured by a method defined in Japanese Industrial Standard JIS K 1557.
In the present invention, the polyol component consists essentially of polyol (1) and polyol (2). The polyol (1) and the polyol (2) may each be a mixture of a plurality of types of polyols, but the ratio of the polyol (1) and the polyol (2) as the mixture is in the above range.

As the isocyanate used in the coated granular fertilizer of the present invention, any one of aromatic polyisocyanates, aliphatic polyisocyanates and alicyclic isocyanates and derivatives thereof can be used. An aromatic polyisocyanate is a compound in which a plurality of isocyanate groups are bonded on an aromatic ring (benzene ring, naphthalene ring, etc.), such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI). Xylylene diisocyanate (XDI), naphthalene 1,5-diisocyanate (NDI), tetramethylene xylylene diisocyanate (TMXDI), polymethylene polyphenyl polyisocyanate (polymeric MDI). Examples of the aliphatic isocyanate include hexamethylene diisocyanate (HDI), dimer acid diisocyanate (DDI), and norbornene diisocyanate (NBDI). Examples of the alicyclic isocyanate include isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), and hydrogenated XDI. In addition, lysine triisocyanate, lysine diisocyanate, and the like can also be used as polyisocyanate. Examples of the polyisocyanate derivative include modified products such as isocyanurate, biuret and uretdione.
As the isocyanate, two or more polyisocyanates may be mixed and used. In the present invention, aromatic isocyanate is preferred from the viewpoints of substance permeation controllability and biodegradability. From the viewpoint of work safety, polymethylene polyphenyl polyisocyanate (polymeric MDI) is preferred.

The coated granular fertilizer of the present invention is characterized in that it is coated with a polyurethane resin obtained by reacting the above-mentioned polyol and isocyanate. The blending amount of the polyol and the isocyanate is the hydroxyl group in the polyol. The equivalent ratio of isocyanate groups in the isocyanate is in the range of 0.9: 1 to 1.2: 1.
The polyurethane resin in the present invention can be produced by adding a polyol containing polyol (1) and polyol (2), and an isocyanate, and if necessary, a catalyst, a surfactant, an extender, a pigment and the like. .

The reaction between the polyol and the isocyanate is not particularly limited. For example, a method in which all polyols and polyisocyanate are mixed and cured / molded, a part of the polyols and isocyanate are mixed in advance, and an isocyanate-terminated prepolymer. After the preparation, the remaining polyol can be mixed and cured / molded. Alternatively, a method in which a small amount of an organic solvent is mixed together and the reaction and solvent removal are simultaneously performed can also be performed. The reaction conditions can be arbitrarily selected. However, when the temperature is increased, the reaction rate between the hydroxyl group and the isocyanate group increases. Furthermore, the reaction rate can be accelerated by adding a catalyst.

Examples of the catalyst used in the production of the polyurethane resin used in the present invention include potassium acetate, calcium acetate, stannous octoate, dibutyltin diacetate, dibutyltin dichloride, dibutyltin dilaurate, dibutylthiotinic acid, octylic acid first. Tin, di-n-octyltin dilaurate, isopropyl titanate, bismuth 2-ethylhexanoate, phosphine, Zn neodecanoate and other organometallic metals, triethylamine, N, N, N ′, N′-tetramethylethylenediamine, triethylenediamine, N-methylmorpholine, N, N-dimethyldidodecylamine, N-dodecylmorpholine, N, N-dimethylcyclohexylamine, N-ethylmorpholine, dimethylethanolamine, N, N-dimethylbenzyl Min, tetrabutyl titanate, oxy isopropyl vanadate, n- propyl zirconate, 2,4,6-tris (dimethylaminomethyl) include amine catalysts such as phenol.
When the catalyst is used, the amount of the catalyst is usually about 0.05 to 5% by weight based on the total weight of the isocyanate and the polyol.

In addition, in the polyurethane film, pigments and dyes for coloring such as titanium oxide and iron oxide; talc, kaolin, silica, carbon, if necessary, within the allowable range in the performance of the present granular coated fertilizer An inorganic / organic powder as a filler such as black, resin powder, clay, etc .; a surfactant or the like may be contained.

The granular fertilizer used in the present invention is a granular material containing a fertilizer component. The fertilizer component is a component containing various elements such as nitrogen, phosphorus, potassium, silicon, magnesium, calcium, manganese, boron, etc. that are applied to the soil to give nutrients in plant cultivation such as paddy rice. Is urea, ammonium nitrate, ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, sodium nitrate, calcium nitrate, potassium nitrate, lime nitrogen, formaldehyde processed urea fertilizer (UF), acetaldehyde processed urea fertilizer (CDU), isobutyraldehyde processed Nitrogenous fertilizers such as urea fertilizer (IBDU) and guanneaurea (GU); superphosphate lime, heavy superphosphate lime, molten phosphorus fertilizer, humic phosphate fertilizer, calcined phosphorous fertilizer, heavy calcined phosphorus, bitter hyperphosphorus Acid, ammonium polyphosphate, potassium metaphosphate, calcium metaphosphate, Phosphoric fertilizers such as soil phosphoric acid, ammonium sulfate, potassium phosphate, ammonium phosphate; potassium fertilizers such as potassium chloride, potassium sulfate, potassium sulfate, potassium sulfate bitter clay, potassium bicarbonate, potassium phosphate; silicic acid Silicic fertilizers such as calcium; Magnesium fertilizers such as magnesium sulfate and magnesium chloride; Calcium fertilizers such as quick lime, slaked lime and calcium carbonate; Examples include ordinary fertilizers (including complex fertilizers) stipulated in the Fertilizer Control Law, such as boron fertilizers such as acid salts. Among them, one containing at least one fertilizer component selected from nitrogen (N), phosphorus (P) and potassium (K), particularly one containing all three types of fertilizer components is preferable. Specific examples thereof include an NPK component type (N-P2O5-K2O) fertilizer, and as such a fertilizer, for example, 5-5-7 (meaning a weight ratio of N-P2O5-K2O; the same shall apply hereinafter). 1-12 flat type such as 12-12-16, 2 type horizontal type such as 5-5-5, 14-14-14, 3 type flat down type such as 6-6-5, 8-8-5, etc. 4-7-9, 6-8-11, etc. 4 type ascending type, 4-7-7, 10-20-20 etc., 5 type ascending flat type, 4-7-4, 6-9-6 etc. 6 type mountain type, 7 type valley type such as 6-4-5, 14-10-13, etc., 8 type falling flat type such as 6-5-5, 18-11-11, etc., 7-6-5, 14 Nine-type down type such as -12-9, 10-type NP type such as 3-20-0 and 18-35-0, 11-type NK type such as 16-0-12 and 18-0-16, 0-3 -14, 0-15-15 It includes 12-inch PK type is.

The granular fertilizer can also contain agricultural chemical components such as herbicides and insecticides. The agrochemical component can be present, for example, in a state of adhering to the surface of the granular fertilizer, or in a state dispersed inside or throughout the granular fertilizer. Particulate fertilizers containing agrochemical ingredients are, for example, sprayed on the surface of fertilizer particles with an aqueous solution of an agrochemical ingredient to be contained, a solution such as an organic solvent, or an emulsion solution further added with a surfactant, and allowed to penetrate into the fertilizer particles. At the same time or after that, the solvent can be removed by evaporation or the like.
The particle size (circular equivalent diameter) of the granular fertilizer is usually in the range of 1 to 5 mm from the viewpoint of production.

The polyurethane coating can be formed on the surface of the granular fertilizer by, for example, reacting (curing) a mixture of polyol and isocyanate with granular fertilizer in a fluidized state or rolling state or a granular fertilizer coated with a hydrophobic compound. .
When a polyol and a catalyst are mixed to prepare a preliminary preparation, the preparation method can include heating and dissolving at about 85 ° C. to 95 ° C. and uniform mixing. The adjustment of the uncured urethane resin by mixing is preferably performed immediately before coating on the granular fertilizer.

The coated granular fertilizer of the present invention is obtained by coating the surface of the granular fertilizer with an uncured urethane resin and then curing the uncured urethane resin.
As a method of coating the surface of the granular fertilizer with uncured urethane resin, the uncured urethane resin is sprayed on the granular fertilizer that is made into a fluidized state by a fluidizing device or a jet fluidizing device, or in a rolling state by a rotating pan or a rotating drum, Examples of the addition and mixing method include dropping.
As a method of curing the uncured urethane resin coated on the surface of the granular fertilizer, the granular fertilizer coated with the uncured urethane resin in a fluidized state or a rolling state as described above is used when the uncured urethane resin is coated. Examples thereof include a method of maintaining a flow or rolling state for a predetermined time under the same temperature condition. In addition, when coating the surface of the granular fertilizer with an uncured urethane resin, the coating and curing can be performed quickly by exposing the granular fertilizer to the hot air, so that the coating is uniform and the coating due to adhesion between particles. It is preferable in terms of prevention of breakage and shortening of curing time.

In addition, the surface of the granular fertilizer in a fluidized state or a rolling state is coated with an uncured urethane resin in an amount such that the thickness of the polyurethane coating is 1 to 10 μm on the granular fertilizer, and is further cured. The method of covering the cured urethane resin and curing one or more times to make a multilayer coating and covering the polyurethane film until the predetermined coating amount is achieved, prevents the formation of lumps of granular fertilizers due to thickening of the resin during curing In addition, it is preferable for industrial production from the viewpoint of prevention of peeling of the film.

In the coated granular fertilizer of the present invention, the amount of the polyurethane coating is usually 6 to 16 parts by weight with respect to 100 parts by weight of the granular fertilizer. The amount of the polyurethane film is substantially the same as the amount of the uncured polyurethane resin to be added.
Since the polyurethane resin in this invention is excellent in the initial elution suppression effect of a fertilizer component, it can suppress the initial elution of a fertilizer component with a small coating amount compared with a normal polyurethane resin.

The coated granular fertilizer of the present invention can be used in paddy fields and can also be used in fields. The application amount varies depending on the type and amount of fertilizer components contained in the coated granular fertilizer, the target plant, the fertilization time, etc., but is usually 10 to 60 kg per 10 ares. Since the coated granular fertilizer of the present invention is excellent in the effect of suppressing the initial elution of the fertilizer components, it can be applied in the vicinity of plant seeds and seedlings where fertilizer damage is a problem. As an application method, it can carry out by the method used in normal granular fertilizer.

Hereinafter, the present invention will be described in more detail with reference to production examples, test examples, and the like, but the present invention is not limited to these examples.

Example 1
5 kg of granular urea (average particle size: 3.0 mm) was charged into a temperature-controllable rolling type coater equipped with a hot air generator, and rotated at 24 RPM to bring the granular fertilizer into a rolling state. The temperature of the granular urea charged by heating the apparatus was maintained at 69 ° C. and maintained in a rolling state, and then the polyols described in Table 1 below and 2,4,6-tris (dimethylaminomethyl) Uncured urethane resin obtained by stirring and mixing a uniform mixture of 0.52 g of phenol and 10.46 g of polymethylene polyphenyl polyisocyanate (polymeric MDI, NCO weight percentage 31%, manufactured by Sumika Bayer Polyurethane) Was quickly added to the granular urea in a rolling state at 69 ° C. to maintain the temperature condition and the rolling state. Subsequently, the operation of adding an uncured urethane resin composition having the same composition as described above and rolling for 3 minutes and 30 seconds was repeated a total of 17 times. Subsequently, after adding 2.5 g of ferric oxide (specific gravity: 4.9 to 5.2, average particle size 0.1 to 2.0 μm, 120ED, manufactured by Toda Kogyo Co., Ltd.) and rolling for 5 minutes, The operation of adding the uncured urethane resin composition and rolling it for 3 minutes and 30 seconds is repeated twice, and after adding 2.5 g of ferric oxide and rolling for 5 minutes, the uncured urethane resin The composition was added and rolled at 69 ° C. for 3 minutes and 30 seconds. Subsequently, 1 g of polyoxyethylene oleyl ether (Pegnol O-16, manufactured by Toho Chemical Co., Ltd.) was added and rolled for 10 minutes. Thereafter, 4 g of wax stone clay (special snow cut clay, Showa Mining Co., Ltd.) was added and rolled for 3 minutes to obtain a coated granular fertilizer.

Example 2
5 kg of granular urea (average particle size: 3.0 mm) was charged into a temperature-controllable rolling type coater equipped with a hot air generator, and rotated at 24 RPM to bring the granular fertilizer into a rolling state. The temperature of the granular urea charged by heating the apparatus was maintained at 69 ° C. and maintained in a rolling state, and then the polyols described in Table 1 below and 2,4,6-tris (dimethylaminomethyl) Uncured urethane resin obtained by stirring and mixing a uniform mixture of 0.43 g of phenol and 9.65 g of polymethylene polyphenyl polyisocyanate (polymeric MDI, NCO weight percentage 31%, manufactured by Sumika Bayer Polyurethane) Was quickly added to the granular urea in a rolling state at 69 ° C. to maintain the temperature condition and the rolling state. Subsequently, the operation of adding an uncured urethane resin composition having the same composition as described above and rolling for 3 minutes and 30 seconds was repeated a total of 17 times. Subsequently, after adding 2.5 g of ferric oxide (specific gravity: 4.9 to 5.2, average particle size 0.1 to 2.0 μm, 120ED, manufactured by Toda Kogyo Co., Ltd.) and rolling for 5 minutes, The operation of adding the uncured urethane resin composition and rolling it for 3 minutes and 30 seconds is repeated twice, and after adding 2.5 g of ferric oxide and rolling for 5 minutes, the uncured urethane resin The composition was added and rolled at 69 ° C. for 3 minutes and 30 seconds. Subsequently, 1 g of polyoxyethylene oleyl ether (Pegnol O-16, manufactured by Toho Chemical Co., Ltd.) was added and rolled for 10 minutes. Thereafter, 4 g of wax stone clay (special snow cut clay, Showa Mining Co., Ltd.) was added and rolled for 3 minutes to obtain a coated granular fertilizer.

Comparative Example 1
5 kg of granular urea (average particle size: 3.0 mm) was charged into a temperature-controllable rolling type coater equipped with a hot air generator, and rotated at 24 RPM to bring the granular fertilizer into a rolling state. The temperature of the granular urea charged by heating the apparatus was maintained at 69 ° C. and maintained in a rolling state, and then the polyols described in Table 1 below and 2,4,6-tris (dimethylaminomethyl) Uncured urethane resin obtained by stirring and mixing a uniform mixture of 0.58 g of phenol and 11.61 g of polymethylene polyphenyl polyisocyanate (polymeric MDI, NCO weight percentage 31%, manufactured by Sumika Bayer Polyurethane) Was quickly added to the granular urea in a rolling state at 69 ° C. to maintain the temperature condition and the rolling state. Subsequently, the operation of adding an uncured urethane resin composition having the same composition as described above and rolling for 3 minutes and 30 seconds was repeated a total of 17 times. Subsequently, after adding 2.5 g of ferric oxide (specific gravity: 4.9 to 5.2, average particle size 0.1 to 2.0 μm, 120ED, manufactured by Toda Kogyo Co., Ltd.) and rolling for 5 minutes, The operation of adding the uncured urethane resin composition and rolling it for 3 minutes and 30 seconds is repeated twice, and after adding 2.5 g of ferric oxide and rolling for 5 minutes, the uncured urethane resin The composition was added and rolled at 69 ° C. for 3 minutes and 30 seconds. Subsequently, 1 g of polyoxyethylene oleyl ether (Pegnol O-16, manufactured by Toho Chemical Co., Ltd.) was added and rolled for 10 minutes. Thereafter, 4 g of wax stone clay (special snow cut clay, Showa Mining Co., Ltd.) was added and rolled for 3 minutes to obtain a coated granular fertilizer.

Comparative Example 2
5 kg of granular urea (average particle size: 3.0 mm) was charged into a temperature-controllable rolling type coater equipped with a hot air generator, and rotated at 24 RPM to bring the granular fertilizer into a rolling state. The temperature of the granular urea charged by heating the apparatus was maintained at 69 ° C. and maintained in a rolling state, and then the polyols described in Table 1 below and 2,4,6-tris (dimethylaminomethyl) Uncured urethane resin obtained by stirring and mixing a uniform mixture of 0.42 g of phenol and 8.39 g of polymethylene polyphenyl polyisocyanate (polymeric MDI, NCO weight percentage 31%, manufactured by Sumika Bayer Polyurethane) Was quickly added to the granular urea in a rolling state at 69 ° C. to maintain the temperature condition and the rolling state. Subsequently, the operation of adding an uncured urethane resin composition having the same composition as described above and rolling for 3 minutes and 30 seconds was repeated a total of 17 times. Subsequently, after adding 2.5 g of ferric oxide (specific gravity: 4.9 to 5.2, average particle size 0.1 to 2.0 μm, 120ED, manufactured by Toda Kogyo Co., Ltd.) and rolling for 5 minutes, The operation of adding the uncured urethane resin composition and rolling it for 3 minutes and 30 seconds is repeated twice, and after adding 2.5 g of ferric oxide and rolling for 5 minutes, the uncured urethane resin The composition was added and rolled at 69 ° C. for 3 minutes and 30 seconds. Subsequently, 1 g of polyoxyethylene oleyl ether (Pegnol O-16, manufactured by Toho Chemical Co., Ltd.) was added and rolled for 10 minutes. Thereafter, 4 g of wax stone clay (special snow cut clay, Showa Mining Co., Ltd.) was added and rolled for 3 minutes to obtain a coated granular fertilizer.

*1：Ｃ３−Ｃ６のトリオールのプロピレンオキサイド付加物（水酸基価３７２ｍｇＫＯＨ／ｇ）
*2：約９０％含量リシノール酸トリグリセリド（水酸基価１６１ｍｇＫＯＨ／ｇ）
*3：〔ポリオール（１）の重量×ポリオール（１）の水酸基価〕／〔ポリオール（２）の重量×ポリオール（２）の水酸基価〕

* 1: Propylene oxide adduct of C3-C6 triol (hydroxyl value 372 mgKOH / g)
* 2: About 90% ricinoleic acid triglyceride (hydroxyl value 161 mgKOH / g)
* 3: [weight of polyol (1) × hydroxyl value of polyol (1)] / [weight of polyol (2) × hydroxyl value of polyol (2)]

Test example (measurement of initial elution suppression effect of fertilizer components)
7.50 g of each of the coated granular urea obtained in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 was weighed into a sample bottle, and 100 ml of distilled water was added. After storage at 25 ° C. for 40 days, 0.5 ml of the supernatant was collected and the amount of urea eluted in water was measured. The elution rate (%) was calculated according to the following formula. The results are shown in Table 2.
Elution rate (%) = (weight of urea eluted in water / total weight of urea) × 100

*4：溶出率（％）基準
◎：０％以上で、１０．０％以下
○：１０．０％より大きく、２０．０％以下
△：２０．０％より大きく、４０．０％以下
×：４０．０％より大きい

* 4: Elution rate (%) standard ◎: 0% or more, 10.0% or less ○: greater than 10.0%, 20.0% or less △: greater than 20.0%, 40.0% or less × : Greater than 40.0%

The coated granular fertilizer of this invention is excellent in the initial elution suppression effect of a fertilizer component.

Claims (4)

A polyol (1) having a ratio of carbon atoms / oxygen atoms in the molecule of 3.0 or less and a polyol (2) having a ratio of carbon atoms / oxygen atoms in the molecule of 5.0 or more are shown below. A polyol containing a ratio satisfying the calculation formula;
Coated granular fertilizer coated with polyurethane resin obtained by reacting with isocyanate.
[Weight of polyol (1) x hydroxyl value of polyol (1)]
/ [Weight of polyol (2) × hydroxyl value of polyol (2)] = 2.4 to 6.0 A polyol (1) having a ratio of carbon atoms / oxygen atoms in the molecule of 3.0 or less and a polyol (2) having a ratio of carbon atoms / oxygen atoms in the molecule of 5.0 or more are shown below. A polyol containing a ratio satisfying the calculation formula;
Coated granular fertilizer coated with polyurethane resin obtained by reacting with isocyanate.
[Weight of polyol (1) x hydroxyl value of polyol (1)]
/ [Weight of polyol (2) × hydroxyl value of polyol (2)] = 2.4 to 4.8 The coated granular fertilizer according to claim 1 or 2, wherein at least one of the polyol (1) and the polyol (2) is a trifunctional or higher functional polyol. The coated granular fertilizer according to claim 1, 2 or 3, wherein the isocyanate is an aromatic isocyanate.