JP6706899B2 - Coated granular fertilizer - Google Patents

Description

The present invention relates to a coated granular fertilizer in which the surface of a coating layer coated with a granular fertilizer with a resin or the like is hydrophilized.

BACKGROUND ART Coated granules of bioactive substances such as fertilizers and pesticides having a coating layer containing a resin have been put into practical use for the purpose of controlling elution, preventing moisture absorption, preventing caking, and preventing dust generation. The use situation of the coated fertilizer varies depending on its use, but it is often used in water such as in paddy fields and hydroponics. Many of these coated fertilizers contain a resin having poor hydrophilicity. Resins generally have a poor affinity with water and strong water repellency, and thus have a property that they easily float when used in, for example, paddy fields. Even when applied to fields, it tended to be exposed on the soil surface due to irrigation and rainfall.

In order to prevent the above-mentioned floating, a method of imparting hydrophilicity to the coating film of the coated fertilizer has been studied. As a technique for imparting hydrophilicity to a resin-containing coating, a coated fertilizer in which a surfactant is dispersed in the coating and fine powder is attached to the coating surface is disclosed (see Patent Document 1). Further, a coated fertilizer in which a fatty acid metal salt or a fatty acid metal salt and an inorganic powder are held on the surface of the coating (see Patent Document 2), and a floating fertilizer coated fertilizer in which hydrous fine powder silicon oxide is attached to the surface of the coating ( Patent Reference 3), coated fertilizer in which hydrous amorphous silicon dioxide fine powder is attached to the surface of the coating (see Patent Literature 4), coated fertilizer in which inorganic fine powder and a surfactant are attached to the surface of the coating (Patent Literature 5). ), diatomaceous earth or water-containing amorphous silicon dioxide fine powder and a coated fertilizer having a surfactant attached to the surface of the fertilizer (see Patent Document 6), a coated fertilizer having a nonionic surfactant attached to the particle surface (Patent Document 7) are disclosed.

Furthermore, even in the case of coated fertilizers with strong water repellency, a coating that provides the optimum floating prevention effect and its sustainability when applying it to paddy fields, and prevents the solidification of fertilizer particles during the production of coated fertilizers. A coated fertilizer whose surface is treated with an amino acid salt and/or a water-soluble polymer compound (see Patent Document 8) capable of obtaining a fertilizer is disclosed. However, although it is possible to have one or two functions out of the three functions of caking prevention, dust generation prevention, and floating prevention, none of them have all three functions.

JP-A-60-29679 JP, 2009-242195, A JP-A-3-232788 Japanese Patent Laid-Open No. 10-130014 JP, 10-167868, A JP-A-2000-128684 JP, 2005-41700, A JP, 2006-327841, A

The present invention is a granular fertilizer (hereinafter referred to as "coated fertilizer" in the present specification) having a coating layer containing a resin having water repellency on the surface thereof, and preventing caking and dust generation even after long-term storage. In addition, it is an object of the present invention to provide a coated fertilizer that can prevent floating on the water surface during application, that is, can simultaneously prevent solidification, dust generation, and floating.

As a result of extensive studies to solve the problems of the conventional techniques, the coating layer of the coated fertilizer has a hydrophilic property imparted to the coating layer by attaching a water-soluble inorganic powder which is inexpensive and easily available. While preventing the floating of the water surface at the time of application, it is found that there is a well-balanced function and effect that caking and dust generation after long-term storage are suppressed, and that the above problems can be solved, and the present invention is completed based on this finding. Came to.

The present invention consists of the following.
(1) A coated granular fertilizer having a coating layer containing a resin on the surface of the granular fertilizer, and the water-soluble inorganic powder retained on the surface of the coating layer.
(2) The ratio of the water-soluble inorganic powder is 0.01 to 1.0 parts by weight with respect to 100 parts by weight of the coated fertilizer having a coating layer containing a resin on the surface of the granular fertilizer. Coated granular fertilizer.
(3) The coated granular fertilizer according to (1) or (2), wherein the water-soluble inorganic powder has a particle size of 0.1 to 150 μm.
(4) The coated granular fertilizer according to any one of (1) to (3), wherein the water-soluble inorganic powder is an alkali metal or alkaline earth metal inorganic acid salt or halide.
(5) The coated granular fertilizer according to (4), wherein the water-soluble inorganic powder is an inorganic acid salt or halide of potassium.

The coated granular fertilizer of the present invention is a useful coated granular fertilizer that prevents floating on the water surface during application and has both the floating prevention effect and the consolidation and dust generation prevention effect even after long-term storage. The "caking" that can be prevented by the present invention is a state in which the fertilizer grains are attached to each other, and not only the state in which they do not collapse even when a strong force such as hitting with a mallet is applied, It also includes the state of collapse by applying a weak force such as touching.

FIG. 1 is a flow sheet of an apparatus for producing a coated fertilizer (that is, for forming a coating layer on the surface of a granular fertilizer).

The coated granular fertilizer according to the present invention is basically a granular fertilizer serving as a core material, a coating layer containing a resin coating the surface of the granular fertilizer, and a water-soluble inorganic powder retained on the surface of the coating layer. It is composed of

The "water-soluble inorganic powder" is powder of a water-soluble inorganic compound. Water solubility represents a property of dissolving a certain amount in water at a predetermined temperature, and as long as the effect of the present invention is exhibited when the inorganic compound powder is held on the surface of the coating layer, the degree of the property. It is not particularly limited. The solubility of the water-soluble inorganic powder in water at 25°C is preferably 1.0 to 50.0% by weight (g/mL), and more preferably 10.0 to 40.0% by weight.

As the water-soluble inorganic compound, an inorganic acid salt (carbonate, sulfate, silicate, phosphate, etc.) or a halide (chloride, etc.) of an alkali metal or an alkaline earth metal is preferable. By holding such a fine powder of a water-soluble inorganic compound, it is possible to achieve both the floating prevention effect and the caking prevention effect.

Particularly, inorganic acid salts or halides of potassium are preferable because they have low hygroscopicity. Among these potassium compounds, potassium chloride or potassium sulfate is preferable because it is less likely to cause stickiness after moisture absorption and is unlikely to cause caking, and potassium sulfate having lower hygroscopicity is more preferable.

The water-soluble inorganic compound used in the present invention is a powder. The particle diameter of the water-soluble inorganic powder is preferably 0.1 to 150 μm, more preferably 1 to 25 μm. When the particle size is in this range, the particles are easily retained on the surface of the coating layer (having good adhesion) and have excellent hydrophilicity, so that the effect of preventing floating is easily exhibited. The water-soluble inorganic powder having such a particle size can be obtained by sieving using a sieve having an appropriate mesh size. For example, a water-soluble inorganic powder that has passed through a sieve having an opening of 25 μm can be regarded as a water-soluble inorganic powder having a particle size of less than 25 μm (usually 1 μm or more).

If the particle size of the water-soluble inorganic powder is appropriate, the higher the retention amount is, the higher the anti-floating effect will be, but the water-soluble inorganic powder will also easily peel off, so the amount of dust generated when handling coated granular fertilizer Will increase. Therefore, the water-soluble inorganic powder to be retained on the surface of the coating layer is preferably 0.01 part by weight or more based on 100 parts by weight of the coated fertilizer from the viewpoint of the floating prevention effect, but at the same time, the dust generation prevention effect From the viewpoint of satisfying it, the proportion of 0.01 to 1.0 parts by weight is preferable, and the proportion of 0.05 to 1.0 parts by weight is more preferable, relative to 100 parts by weight of the coated fertilizer. The retained amount of the water-soluble inorganic powder can be accurately grasped by quantifying the water-soluble inorganic powder dissolved when the coated granular fertilizer is immersed in water, as shown in Examples below. It is preferable to adjust so that almost all of the "addition amount" of the water-soluble inorganic powder in the treatment (surface treatment) for attaching the water-soluble inorganic powder to the coating layer surface of the coated fertilizer becomes the "retention amount". ..

In the present invention, essentially, by holding the water-soluble inorganic powder on the surface of the coating layer, it is possible to simultaneously prevent the above-mentioned solidification, dust generation, and floating. However, if necessary, to the extent that the effects of the present invention are not impaired, polysaccharides such as starch, non-water-soluble inorganic powders such as silica and hydrous amorphous silicon dioxide, aliphatic metal salts, etc. The substance retained (attached) on the surface of the layer may be used together with the water-soluble inorganic powder.

The effect of preventing floating in the present invention is obtained by making the surface hydrophilic by adhering a water-soluble inorganic powder to the surface of a hydrophobic coating layer containing a resin coated with granular fertilizer. On the other hand, granular fertilizer (coated fertilizer) causes solidification due to the presence of water. Therefore, in order to prevent solidification during long-term storage after production, the water-soluble inorganic powder held on the surface of the coating layer has hygroscopicity. It is preferably small.

By the way, when comparing the hygroscopicity of the water-soluble inorganic compound and the water-soluble organic compound, the hygroscopicity of the water-soluble organic compound is generally high and the hygroscopicity of the water-soluble inorganic compound is low. Therefore, in the present invention, the solidification preventing effect is obtained by using the water-soluble inorganic compound instead of the water-soluble organic compound.

The method for holding the water-soluble inorganic powder on the surface of the coating layer is not particularly limited, but a known mixer, for example, a rolling drum, a pan, a device for rolling particles such as a pot mixer, is used to coat the fertilizer. A method of adding a water-soluble inorganic powder while rolling and adhering it to the coating layer can be mentioned. Conditions such as the temperature during the adhesion treatment are not particularly limited, but in order to perform the adhesion efficiently, fusion of the coating layer does not occur, and within the range that does not affect the quality such as the elution behavior of the coated fertilizer. It is recommended to control the conditions related to the adhesion of the water-soluble inorganic powder to the coating layer, such as raising the surface temperature of the coating layer.

Examples of the granular fertilizer in the present invention include nitrogenous fertilizers, phosphate fertilizers, potassium fertilizers, and fertilizers containing essential plant elements such as calcium, magnesium, sulfur, iron, trace elements and silicon. Examples of nitrogenous fertilizers include ammonia sulfate, urea, and ammonium nitrate, as well as isobutyraldehyde condensed urea and acetaldehyde condensed urea. Examples of the phosphate fertilizer include lime superphosphate, fused phosphorus fertilizer, and calcined phosphorus fertilizer. Examples of potassium fertilizers include potassium sulfate, chloride chloride, and silica silicate fertilizer. The form of fertilizer is not particularly limited. Further, advanced chemical fertilizers and compound fertilizers having a total content of the three components of fertilizers (nitrogen, phosphoric acid, potassium) of 30% or more, and further organic fertilizers may be used. Further, a fertilizer containing a nitrification inhibitor or a pesticide may be used.

As a granulation method for the granular fertilizer, an extrusion granulation method, a fluidized bed granulation method, a tumbling granulation method, a compression granulation method, a coating granulation method, an adsorption granulation method, or the like can be used. Any of these granulation methods may be used in the present invention.

The particle size of the coated fertilizer used in the present invention is not particularly limited, but it is preferably 1.0 to 10.0 mm. More preferably, 2.0 to 4.0 mm contains 90% by weight or more, and these can be easily obtained by adjusting the sieve opening.

Like the conventional coated fertilizer, the coating layer of the coated granular fertilizer of the present invention has a function of coating the surface of the granular fertilizer and gradually eluting the fertilizer component (that is, imparting the sustained release property). The resin that can be used for the coating layer is not particularly limited, and may be either a thermoplastic resin or a thermosetting resin. Above all, from the viewpoint of environmental protection, it is preferable to use a photodegradable resin or a biodegradable resin, or to use a resin composition containing them.

Examples of thermoplastic resins include olefin polymers, vinylidene chloride polymers, diene polymers, waxes, polyesters, petroleum resins, natural resins, fats and oils and modified products thereof.

As the olefin polymer, low density polyethylene (density 0.88 to 0.93 g/cm ³ ), high density polyethylene (density 0.94 to 0.97 g/cm ³ ), linear low density polyethylene, ultra low Density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 1-40% by weight), and ethylene-α-olefin copolymer (density 0.88-0.94 g/cm ³ ), polypropylene, ethylene-polypropylene Copolymer, ethylene-butadiene copolymer, ethylene-carbon monoxide copolymer, ethylene-hexene copolymer, polybutene, butene-ethylene copolymer, butene-propylene copolymer, polystyrene, ethylene-vinyl acetate- Examples thereof include carbon monoxide copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers and ethylene-methacrylic acid ester copolymers. Examples of vinylidene chloride-based polymers include vinylidene chloride-vinyl chloride copolymers and hydrides of diene-based polymers. The melt flow rate, the molecular weight, the molecular weight distribution, the catalyst used, the manufacturing process, etc. of the above resin are not particularly limited.

As the diene polymer, a terpolymer such as a butadiene polymer, an isoprene polymer, a chloroprene polymer, a butadiene-styrene copolymer, an EPDM polymer, a styrene-isoprene copolymer, or a butadiene-ethylene-methacrylic acid copolymer is used. A copolymer can be illustrated.

Examples of waxes include beeswax, wood wax, paraffin, and polyethylene wax, examples of polyester include aliphatic polyesters such as polylactic acid and polycaprolactone, and aromatic polyesters such as polyethylene terephthalate, and examples of natural resins include natural rubber. , Rosin and the like, and examples of fats and oils and modified products thereof include hardened products, solid fatty acids and metal salts.

Examples of the thermosetting resin include phenol resin, alkyd resin, unsaturated polyester, epoxy resin, silicon resin, urethane resin and drying oil. These thermosetting resins have many combinations of monomers, but the types and combinations of the monomers are not limited in the present invention. In addition to a polymer of monomers, a polymer of a dimer or a polymer, or a mixture thereof may be used. It may also be a mixture of a plurality of different types of resins.

As a filler in the coating layer of coated granular fertilizer, talc, mica, seritite, glass flakes, various metal foils, graphite, BN (hexagonal), MIO (plate iron oxide), plate calcium carbonate, plate Plate-like filler such as aluminum hydroxide; spherical filler such as calcium carbonate, silica, clay, various ore crushed products, starch and the like; sulfur and the like can be added.

When the coating layer contains a filler, the content ratio thereof is not particularly limited, but is preferably 5 to 90 parts by weight, and more preferably 20 to 60 parts by weight with respect to the resin.

The coating layer of the coated granular fertilizer may optionally contain, as a surfactant, a nonionic surfactant represented by a fatty acid ester of polyol, a nonionic surfactant, or the like. When the coating layer contains a surfactant, the content ratio thereof is not particularly limited, but is preferably 0.01 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight with respect to the resin.

Various organometallic compounds may optionally be added to the coating layer of the coated granular fertilizer in order to decompose the resin contained in the coating layer. Examples of the organic metal compound include organic metal complexes and organic acid metal salts. Of these, iron complexes and iron carboxylates are preferable because their photodegradability can be easily adjusted. Examples of the iron complex include iron acetylacetonate, iron acetonyl acetonate, iron dialkyldithiocarbamate, dithiophosphate, xanthate, and benzthiazole. Examples of iron carboxylates include iron compounds such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, behenic acid, oleic acid, linoleic acid, and linolenic acid. These may be added alone or in combination of two or more. The proportion of the organometallic compound in the coating layer is preferably 0.0001 to 1 part by weight, more preferably 0.001 to 0.5 part by weight. With the above proportion, disintegration or degradability is obtained after using the coated granular fertilizer, and the initial quality is maintained during storage.

The method for producing the coated fertilizer, that is, the method for forming the coating layer on the surface of the granular fertilizer is not particularly limited. For example, a method of spraying a molten resin and the above-described additives (which are referred to as resins, etc.) used as necessary on the surface of the granular fertilizer, a solution or emulsion in which the resin or the like is dissolved or suspended in a solvent is used as the granular fertilizer Method of spraying on the surface (hereinafter referred to as "solution spray method"), method of adhering powder such as resin on the surface of granular fertilizer, then melting to form a film, spraying monomer on the surface of granular fertilizer, and reacting on the surface It can be produced by a method of making it into a resin (coating), and a dipping method in which granular fertilizer is dipped in a melt or a solution of a resin or the like.

The thickness of the coating layer can be appropriately selected depending on the type and composition of the resin and the like, the size of the granular fertilizer, and the elution pattern of the intended fertilizer component, but it is preferably 10 to 100 μm on average, and more preferably 20 to 70 μm. The coating rate of the coating layer (ratio of the weight of the coating layer to the coated fertilizer) is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

1. Production of Coated Fertilizer Using the production apparatus shown in FIG. 1, a coating layer was formed on the surface of granular urea by the following method. In the manufacturing apparatus, hot air flows from the lower part to the upper part of the fluidized bed 1 and passes through the dust collector 6, the condenser 7 cools the gas, and the solvent is condensed and recovered. The gas that has passed through the condenser 7 is circulated so that it is heated from the blower 8 through the heater 12 and heated to be introduced into the fluidized bed 1 again as hot air. By adopting such a closed system, the solvent will not be discharged to the outside.

As the particles 3, 15 kg of granular urea (particle diameter 2.0 to 4.0 mm, average particle diameter 3.0 mm) is introduced through the inlet provided on the side surface of the fluidized bed 1, and hot air introduced from the lower part of the fluidized bed 1 And it was made to be in a fluidized state with a stirring bath installed at the bottom of the fluidized bed 1. At this time, the hot air flow rate and the hot air temperature were adjusted so that the particle temperature was 60±2°C. The hot air flow rate was adjusted while measuring with a flow meter installed between the blower 9 and the fluidized bed 1, and the hot air temperature was adjusted while measuring the particle temperature and the exhaust temperature (fluid bed 1 upper temperature).

On the other hand, polyethylene (low density polyethylene, density 0.923 g/cm ³ (JIS K 6760), melt flow rate (MFR) 0.3 g/10 min. (JIS K 6760)) 50 weight as the composition of the coating layer in the dissolution tank 9. Parts, 5 parts by weight of corn starch, 45 parts by weight of talc (average particle size 10 μm), 0.01 parts by weight of iron stearate and 1900 parts by weight of tetrachloroethylene are added, and mixed and stirred at 100±2° C. for 30 minutes. The resin was dissolved to prepare a uniform spray solution 5 having a concentration of 5% by weight. The dissolution tank 9 was constantly stirred until the coating was completed.

The spray liquid 5 was transported to the spray nozzle 2 installed in the upper part of the fluidized bed 1 at a flow rate of about 110 kg/h, and sprayed on the flowing granular urea. Tetrachloroethylene contained in the sprayed spray liquid is condensed and collected by the condenser 7, stored in the tank 11, and guided to the dissolution tank 9.

The above-mentioned coating operation was started from the time when the temperature of the flowing granular urea reached 60° C., and was carried out until the coating amount was 12% by weight based on the final coated fertilizer. Thereafter, while keeping in mind that the particle temperature was maintained at 60±2° C., only the hot air was blown for 10 minutes while controlling the temperature of the hot air to perform drying. When the drying was completed, the coated granular urea was discharged from the outlet 13 at the bottom of the fluidized bed 1 to obtain a coated fertilizer (coated urea) having a coating layer for controlling the elution rate through desolvation treatment. ..

Conditions for forming coating layer Granular urea: 15 kg
Particle temperature during coating: 60°C
Melting temperature: 100-110°C
Spray liquid temperature: 80-100°C
Hot air temperature: 130-140°C
Spray flow rate: 108kg/h
2. Floating prevention treatment of coating layer surface (Example 1)
A pulverizer (trade name: Millser IFM-800DG, manufactured by Iwatani Sangyo Co., Ltd.) was used to pulverize potassium chloride for 30 seconds and sieve the powder to obtain a fine powder. 100 parts by weight of the coated urea obtained in “1. Preparation of coated fertilizer” was immediately put into a rotary drum type rolling device (diameter 90 mm) after the production, and then potassium chloride fine powder sieved to less than 25 μm was added. 3 parts by weight was added. A coated granular fertilizer of the present invention (Example 1) was obtained by rolling at 60 rpm for 10 minutes to adhere to the surface of the coated urea. The solubility of potassium chloride in water at 25°C is 36% by weight.

(Example 2)
In "2. Floating prevention treatment of coating layer surface", the treatment is carried out in the same manner as in Example 1 except that fine powder of potassium chloride sieved at 25 µm or more and 150 µm or less is used and the addition amount is changed to 0.1 part by weight. Thus, the coated granular fertilizer of the present invention (Example 2) was obtained.

(Example 3)
In "2. Floating prevention treatment of coating layer surface", the treatment is carried out in the same manner as in Example 1 except that potassium chloride fine powder sieved at 25 µm or more and 150 µm or less is used and the addition amount is changed to 0.5 part by weight. Thus, the coated granular fertilizer of the present invention (Example 3) was obtained.

(Example 4)
In "2. Floating prevention treatment of coating layer surface", the treatment is carried out in the same manner as in Example 1 except that potassium chloride fine powder sieved at 25 µm or more and 150 µm or less is used and the addition amount is changed to 1.0 part by weight. Thus, the coated granular fertilizer of the present invention (Example 4) was obtained.

(Example 5)
In “2. Floating prevention treatment of coating layer surface”, by treating according to Example 1 except that potassium chloride fine powder sieved with a size larger than 150 μm is used and the addition amount is changed to 0.3 part by weight. A coated granular fertilizer (Example 5) of the present invention was obtained.

(Example 6)
In "2. Floating prevention treatment of coating layer surface", potassium chloride was replaced with potassium sulfate, and the other conditions were treated according to Example 1, to obtain the coated granular fertilizer of the present invention (Example 6). Obtained. The solubility of potassium sulfate in water at 25° C. is 12% by weight.

(Example 7)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm was replaced with potassium sulfate fine powder sieved at 25 μm or more and 150 μm or less, and other conditions were the same as in Example 1. A coated granular fertilizer of the present invention (Example 7) was obtained by processing according to the above method.

(Example 8)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm is replaced with potassium sulfate fine powder sieved at 25 μm or more and 150 μm or less, and the addition amount is 0.05 part by weight. In place of the above, other conditions were treated according to Example 1 to obtain a coated granular fertilizer of the present invention (Example 8).

(Example 9)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm was replaced with the potassium sulfate fine powder sieved at 25 μm or more and 150 μm or less, and the addition amount was changed to 1 part by weight. Further, 0.1 part by weight of cornstarch (particle size 2 to 30 μm, average particle size 15 μm) was mixed and used, and the other conditions were treated according to Example 1 to obtain the coated granular fertilizer of the present invention. (Example 9) was obtained.

(Example 10)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm was replaced with potassium sulfate fine powder sieved at more than 150 μm, and the addition amount was changed to 0.3 parts by weight. The other conditions were treated according to Example 1 to obtain a coated granular fertilizer of the present invention (Example 10).

(Example 11)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm was replaced with sodium carbonate fine powder sieved at 25 μm or more and 150 μm or less, and other conditions were the same as in Example 1. The coated granular fertilizer of the present invention (Example 11) was obtained by processing according to the above method. The solubility of sodium carbonate in water at 25°C is 31% by weight.

(Example 12)
In “2. Floating prevention treatment of coating layer surface”, the potassium chloride fine powder sieved at less than 25 μm was replaced with sodium chloride fine powder sieved at 25 μm or more and 150 μm or less, and other conditions were the same as in Example 1. By treating according to the same manner, a coated granular fertilizer of the present invention (Example 12) was obtained. The solubility of sodium chloride in water at 25°C is 36% by weight.

(Comparative Example 1)
The coated fertilizer that was not subjected to the anti-floating treatment, that is, the coated urea itself obtained in “1. Preparation of coated fertilizer” was used as a coated granular fertilizer as a control product (Comparative Example 1).

(Comparative example 2)
In "2. Floating prevention treatment of coating layer surface", the coating of the control product was carried out according to Example 1 except that potassium chloride (particle diameter less than 25 µm) was changed to kaolin (Kanto Chemical Co., Inc., average particle diameter 1 µm). A granular fertilizer (Comparative Example 2) was obtained.

(Comparative example 3)
In “2. Floating prevention treatment of coating layer surface”, the coating of the control product was carried out in accordance with Example 1 except that potassium chloride (particle size less than 25 μm) was changed to silica fume (made by Tomoe Kogyo Co., Ltd., average particle size 1 μm) A granular fertilizer (Comparative Example 3) was obtained.

(Comparative example 4)
In "2. Floating prevention treatment of coating layer surface", coating of the control product was carried out according to Example 1 except that potassium chloride (particle size less than 25 µm) was changed to bentonite (Kanto Chemical Co., Inc., particle size less than 50 µm). A granular fertilizer (Comparative Example 4) was obtained.

3. Quantification of Retained Amount of Water-Soluble Inorganic Powder With respect to each sample of the above-mentioned examples, the retained amount of the water-soluble inorganic powder was quantified by the following method. From the quantitative results, the "retained amount" was almost the same as the "added amount" in the floating prevention treatment of the above-mentioned embodiment.

5 g of the sample and 100 ml of pure water were placed in a beaker and subjected to ultrasonic treatment for 10 minutes. With respect to the aqueous solution after the treatment, the concentration of the water-soluble inorganic powder was measured by ion chromatography (TO2001, IC2001). On the other hand, as a blank, the same operation was performed on the coated fertilizer using the water-soluble inorganic powder that was not subjected to the floating prevention treatment, and the concentration of the water-soluble inorganic powder was measured. The value obtained by subtracting the measured concentration of the blank from the measured concentration of the sample was converted into the weight of the water-soluble inorganic powder held by the sample, and the ratio to 100 parts by weight of the coated fertilizer was obtained.

4. Evaluation method The coated granular fertilizers of the above-mentioned Examples and Comparative Examples were evaluated as follows by using the samples obtained after the lapse of half a year or more after the production.

(A) Measurement of solidification rate 500 g of a sample was put in a 17.5 cm×17.5 cm polyethylene bag and heat-sealed. The sample was stored under a load of 40 kg at a weight of 30 kg for 2 days. The weight was gently removed and the bag was gently cut to avoid impacting the sample. The solidified portion of the sample was taken out using a brush and the weight was measured to determine the solidification rate (%). Based on the value of the caking rate, the caking evaluation was judged in three grades of ◎○×. If the caking evaluation is ⊚ or ◯, that is, the caking rate is less than 35%, the test is passed.

Solidification rate (%) = (weight of solidified portion/total weight) x 100
Consolidation evaluation
Solidification rate 0 to 10%: ◎
Solidification rate 10-35%: ○
Solidification rate 35% or more: ×
(B) Measurement of Dust Generation A polypropylene container with a lid (width 200 mm, depth 150 mm, height 210 mm) has a hole (diameter 40 mm) for introducing the sample in the center of the lid, and a hole for venting air ( A diameter of 15 mm) was opened beside it. Then, the polypropylene container is covered, and 1 kg of the sample is put into the container from the hole in the center of the cover using a funnel (lower leg diameter 35 mm), and the amount of dust in the container is visually observed in three stages of ◎○×. It was judged. If the dust generation evaluation is ◎ or ○, it passes.
Dust generation evaluation Almost no visual observation ~ cigarette smoke level: ◎
Smoke is visually noticeable: ○
Smell is visually severe and sick: ×
(C) Measurement of levitation ratio After mixing 50 g of the sample with 100 g of black soil of 2 mm path that was air-dried, the sample was spread on a 16 cm x 20 cm vat and 300 ml of water was poured. The bat was vibrated lightly, and the ratio of the number of particles floating on the water surface was obtained as the levitation ratio, and the levitation property was evaluated in three grades of ⊚∘. If the floatation evaluation is ⊚ or ◯, that is, if the floatation rate is less than 30%, it is considered as pass.
Floating rate (%) = (number of floating particles/total number of particles) x 100
Levitation evaluation Levitation rate 0 to 20%: ◎
Ascent rate 20 to 30%: ○
Levitation rate 30% or more: ×
(D) Comprehensive Evaluation When all of the evaluations of consolidation, dust generation, and floatation were ⊚, ⊚ was evaluated as ◯ if there was at least one ◯, and as x if there was at least one x. Passed if ◎ or ○ evaluation. The results are shown in Table 1. As a result of the judgment, all the coated granular fertilizers (Examples) in which the coating layer was surface-treated with the water-soluble inorganic powder were judged as ⊚ or ○. On the other hand, all the coated granular fertilizers (comparative examples) in which the surface treatment of the coating layer was not performed with the water-soluble inorganic powder were evaluated as x.

From this result, by holding the water-soluble inorganic powder on the surface of the coating layer, it has an effect of preventing the granular fertilizer from floating on the water surface even after long-term storage, and also has an effect of preventing solidification and dust generation. It is clear that a coated granular fertilizer is obtained. Moreover, it is understood that various combinations of inorganic acid salts or halides of alkali metals or alkaline earth metals can be used as the water-soluble inorganic powder. Furthermore, it can be seen that if the particle size and the amount of adhesion are adjusted to the optimum range, the floating prevention effect, the caking prevention effect, and the dust generation prevention effect can be simultaneously satisfied at a high level (⊚ evaluation).

1. Fluidized bed 2. Spray nozzle 3. Particle 4. Hot air 5. Spray liquid 6. Dust collector 7. Condenser 8. Blower 9. Dissolution tank 10. Pump 11. Tank 12. Heater 13. Outlet

Claims (7)

A coated granular fertilizer having a coating layer containing a resin on the surface of the granular fertilizer, and having a water-soluble inorganic powder adhered to the surface of the coating layer , wherein the particle diameter of the water-soluble inorganic powder is 0.1 to 150 μm. A coated granular fertilizer having a sustained release property, which prevents floating on the water surface during application . The coated granular fertilizer according to claim 1, wherein the proportion of the water-soluble inorganic powder is 0.01 to 1.0 part by weight with respect to 100 parts by weight of the coated fertilizer having a coating layer containing a resin on the surface of the granular fertilizer. .. The coated granular fertilizer according to claim 1 or 2 , wherein the water-soluble inorganic powder is an inorganic acid salt or halide of an alkali metal or an alkaline earth metal. The coated granular fertilizer according to claim 3 , wherein the water-soluble inorganic powder is an inorganic acid salt or halide of potassium. The coated granular fertilizer according to any one of claims 1 to 4, wherein the water-soluble inorganic powder has a particle diameter of 1 to 25 µm. The coated granular fertilizer according to any one of claims 1 to 5, wherein the water-soluble inorganic powder is a sulfate. A coated granular fertilizer having a coating layer containing a resin on the surface of the granular fertilizer, wherein the water-soluble inorganic powder is attached to the surface of the coating layer, wherein the water-soluble inorganic powder is potassium sulfate.

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