JPH09165285A - Coated granular fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated granular fertilizer capable of adjusting the starting time of dissolution of the fertilizer component in a medium containing water or in water, especially adjusting so that the fertilizer starts to dissolute after passing a relatively long period of time from the time of fertilizing, and good in preservation stability for a long period. SOLUTION: This coated granular fertilizer is obtained by coating the fertilizer granules with a coating layer containing at least three components consisting of a copolymer of an aqueous alkali soluble styrene-based monomer with an unsaturated carboxylic acid, its derivative or an aqueous alkali soluble rosin-based resin, a polymer material neither soluble to water nor to aqueous alkali and an alkaline substance as major components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the elution start time of fertilizer components in a water-containing medium or water, and particularly adjusts the fertilizer components to start elution after a relatively long time has elapsed from the time of fertilization. The present invention relates to a coated granular fertilizer that is capable of long-term storage stability.

[0002]

2. Description of the Related Art In recent years, in agriculture in Japan, the agricultural labor force is becoming weak due to the aging of agricultural workers and depopulation of rural areas. Therefore, as one of the labor saving of agricultural work, mechanization of fertilizer application and utilization of slow-release fertilizer are attempted.

For example, as a slow-release fertilizer, a fertilizer coated with a coating material containing a mixture of α-olefin resin and ethylene-vinyl acetate copolymer as a main component (Japanese Patent Publication No. 60-
21952), a fertilizer coated with a coating material containing a mixture of an olefin resin and an ethylene-vinyl acetate copolymer as a main component and further containing a surfactant (see Japanese Patent Publication No. 60-37074). Coated fertilizer coated with a film containing a polymer such as polyolefins as a binder and containing 50 to 80% by weight of water-insoluble or poorly water-soluble inorganic powder (see Japanese Examined Patent Publication No. 60-3040), olefin-based Granules coated with a mixture of polymer, vinylidene chloride-based polymer, diene polymer, waxes, petroleum resin, and other film-forming materials, and agricultural materials such as fertilizers, soil conditioners, fertilizers, and agricultural chemicals. Agricultural material-coated granular fertilizer in which the fertilizer is further coated with a film-forming material (see JP-A-3-60486) and the like have been proposed.

All of these coated fertilizers have pinholes or cracks caused by imperfections of the coating, or pinholes intentionally made by adding various additives, or water permeability or moisture permeability of the coating. This is a type of coated fertilizer in which the fertilizer component in the fertilizer component is gradually adjusted and eluted by utilizing the fertilizer component.

By the way, in the growth process of plants, the required fertilizer component and its amount differ depending on the time. For example, in paddy rice cultivation, it is necessary to apply fertilizer 4 to 5 times in accordance with the growth of rice from basic manure to hot manure. That is, for each specific period of the growth process of each plant, the required amount of fertilizer necessary for that period is applied, the fertilizer is not given after that period, and at the other time thereafter, similarly. It is desirable to apply the required fertilizer components in the required amount.

However, the conventional coated fertilizer as described above is of a type in which the elution rate of the fertilizer component is adjusted, and the elution rate of the fertilizer component is merely changed. When all fertilizers are first applied as a basic fertilizer, for example, the nitrogen component gradually elutes even when the nitrogen component is not needed, and thus it is necessary to supplement the fertilizer because it is insufficient when a large amount of nitrogen component is required. Become. Therefore, when using conventional coated fertilizer, all fertilizers necessary for plant growth are applied once as the basic fertilizer. Can not be applied sequentially.

Recently, as a coated fertilizer for solving the above-mentioned problems, a first coating layer made of an alkaline substance is formed on the surface of granular fertilizer, and an olefin polymer and an alkali are formed on the surface of the first coating layer. A coated granular fertilizer having a second coating layer formed of a mixture of a water-soluble isobutylene-maleic anhydride copolymer or a modified form thereof has been proposed (see Japanese Patent Laid-Open No. 4-202078).

[0008]

The coated granular fertilizer using the above-mentioned alkaline water-soluble isobutylene-maleic anhydride copolymer or its modified product and an alkaline substance as a coating material is relatively early (about 20 days). After elapse)
It tends to start the elution of fertilizer components, and is suitable as a coated granular fertilizer for such purpose, but it starts elution of the fertilizer components after a long time (for example, 30 days or more) has elapsed from the time of fertilization. It is difficult to produce a coated granular fertilizer with a purpose.

Further, a coated granular fertilizer using a coating material in which an alkaline water-soluble isobutylene-maleic anhydride copolymer or its modified product and an alkaline substance are combined is stored for a long time depending on the type of fertilizer component to be coated. Stability may be unsatisfactory.

[0010]

According to the present invention, fertilizer particles are
A coating layer containing a copolymer of a styrene monomer soluble in alkaline water and an unsaturated carboxylic acid or a derivative thereof, a polymer substance insoluble in water and alkaline water, and at least three components of the alkaline substance as main components. The coated granular fertilizer is characterized by being coated with.
In the present invention, the fertilizer particles are also coated with a coating layer containing at least three components of an alkaline water-soluble rosin resin, a water-insoluble polymeric substance, and an alkaline substance as main components. There is also a coated granular fertilizer characterized by that. The coating material of the coated granular fertilizer of the present invention is such that the amount of the copolymer of styrene monomer and unsaturated carboxylic acid soluble in alkaline water or its derivative (or rosin resin) is the copolymer or its derivative ( Alternatively, the amount of the alkali substance is within the range of 0.1 to 50% by weight of the total amount of the high molecular substance insoluble in water and alkaline water, and the amount of the alkaline substance is the above copolymer or its derivative ( Or 0.0 of the amount of rosin resin)
It is desirable to be in the range of 5 to 5 times by weight.

In the coated granular fertilizer of the present invention, the coating layer is provided in contact with fertilizer particles containing an alkaline substance and a polymeric substance insoluble in both water and alkaline water as main components. , And a copolymer of a styrene monomer soluble in alkaline water and an unsaturated carboxylic acid or a derivative thereof (or a rosin resin) provided as an independent layer outside the first coating layer and water or alkaline water. Also, it is desirable to adopt a configuration including two layers of a second coating layer containing an insoluble polymer substance as a main component. The high molecular substance insoluble in both water and alkaline water is preferably an olefin polymer or copolymer.

In the coated granular fertilizer of the present invention, the surface of the above-mentioned coating layer (the surface not in contact with the fertilizer particles)
On top of that, as a main component, a polymeric substance insoluble in both water and alkaline water, such as an olefin polymer,
A protective coating layer (outermost surface coating layer) made of a coating material containing neither an alkaline water-soluble polymer substance nor an alkaline substance may be formed.

The fertilizer particles used in the coated granular fertilizer of the present invention may be any conventionally known fertilizer particles, but the coating layer of the present invention is constructed in the air at a temperature near room temperature. It is particularly advantageous for fertilizer particles which have a very low or almost no release of ammonia when left to stand. However, when the ammonia-releasing fertilizer particles are coated, between the coating layer of the present invention and the fertilizer particles, a polymer substance soluble in alkaline water alone or other polymer substance (for example, in water) is used. It is also possible to provide a shielding layer made of a mixture of a polymer substance which does not dissolve in alkaline water).
Specific examples of fertilizer particles used for producing the coated granular fertilizer of the present invention include urea, sodium nitrate, aldehyde condensed urea, isobutyraldehyde condensed urea, and other nitrogenous fertilizers, fertilizers, calcined phosphate fertilizers, processed phosphate fertilizers. Phosphate fertilizers such as mixed phosphate fertilizer, corrosive acid phosphate fertilizer, potassium sulfate, chloride chloride, potassium sulfate magnesia, potassium bicarbonate, potassium phosphate fertilizer such as potassium fertilizer, phosphate potassium, nitrate nitrate, etc. Mention may be made of chemical fertilizers, organic fertilizers and the like, and fertilizer particles obtained by granulating a mixture of these fertilizers by a method known per se.
Although the particle size of the fertilizer particles is not particularly limited, it is generally preferably 1 to 4 mm.

The alkaline water-soluble polymer substance used in the present invention is selected from the group consisting of an alkaline water-soluble rosin resin and a copolymer of a styrene monomer and an unsaturated carboxylic acid or a derivative thereof. And at least one alkaline water-soluble polymeric substance.

The above-mentioned alkaline water-soluble polymer substance preferably has a solubility in ammonia water (ammonia concentration: 8% by weight) of about 5 to 80% by weight, particularly about 10 to 60% by weight. It does not dissolve easily in water, or hardly swells even when it comes into contact with water, which prevents the early elution of fertilizer components from the inside of the coated granular fertilizer, and also provides long-term storage stability. It is preferable in ensuring.

The above-mentioned copolymer of styrene monomer and unsaturated carboxylic acid or its derivative is 30 to 70 mol% of styrene monomer, especially 40 to 60 mol%, and 70 to 30 mol% of unsaturated carboxylic acid, especially It is preferably a copolymer with 60 to 40 mol% or a derivative thereof. In addition, in the alkaline water-soluble polymer substance, other monomer components (ethylene, propylene, isobutylene, acrylonitrile, etc.) are partially (preferably 10 mol% with respect to the total monomer components) in place of the both monomer components. Less than,
It may be used particularly preferably in a proportion of 5 mol% or less).

Derivatives of each of the above-mentioned copolymers include those in which the carboxylic acid in the copolymer forms a salt such as an alkali metal, and some of the carboxylic acid (or dicarboxylic acid) may be completely or completely converted by a lower alcohol. Partially esterified, partly amidated or maleimidated with an amine compound, partly modified with natural resin, or the dicarboxylic acid in the copolymer is anhydrous Things are included.

Examples of the styrene-based monomer include styrene and styrene having a substituent such as an alkyl, halogen or nitro group on the benzene ring.
Particularly, styrene having no substituent and styrene having a lower alkyl group as a substituent are preferable. Examples of the unsaturated carboxylic acid include carboxylic acid compounds having a carbon-carbon unsaturated group such as acrylic acid, methacrylic acid, maleic acid and maleic anhydride, and maleic acid and maleic anhydride are particularly preferable. .

As the rosin resin soluble in alkaline water, a rosin resin (containing 80 to 97% of resin acid) obtained by steam distillation of raw pine resin is used as an aliphatic alcohol or an unsaturated alcohol. The rosin resin esterification product or the copolymerization product of unsaturated carboxylic acid compounds such as maleic anhydride and acrylic acid with olefins (eg ethylene, propylene, isobutylene, etc.) is partially modified with the rosin resin. Rosin-modified resin (for example, rosin-modified maleic acid resin), in particular, rosin-modified maleic acid resin in which the carboxylic acid anhydride copolymer is modified with rosin resin (for example, from "Arakawa Chemical Industry Co., Ltd." (Sold under the product name)
Is preferred.

In the present invention, the alkali water-soluble polymer substance is particularly preferably a rosin-modified maleic acid resin, or a copolymer of styrene (which does not contain a substituent) and maleic anhydride or a derivative thereof.

In the present invention, examples of the polymer substance which is not soluble in water and alkaline water, which is used in combination with the above-mentioned alkali water-soluble polymer substance, include olefin polymers, copolymers containing olefins, and diene polymers. Suitable examples thereof include waxes, petroleum resins, natural resins, fats and oils and modified products thereof. In the present invention, the polymeric substance that is insoluble in water and alkaline water means at least 3 even if the polymeric substance is formed into a film and left in contact with water or alkaline water (such as the above-mentioned ammonia water). Month, especially 6 months, means a polymer substance that does not undergo any change in shape such as collapse.

Examples of the above-mentioned olefin polymer include polyethylene, polypropylene, ethylene-propylene copolymer, polybutene, butene-ethylene copolymer, butene-
Propylene copolymer, polystyrene and the like can be mentioned, and as the copolymer containing olefin, ethylene-
Vinyl acetate copolymer, ethylene-ethyl acrylate ester copolymer, ethylene-ethyl methacrylic acid ester copolymer, propylene-ethyl acrylate ester copolymer and the like can be mentioned, further, as the diene-based polymer , Polybutadiene, polyisoprene, polychloroprene, butadiene-styrene copolymer, EPDM polymer, isoprene-styrene copolymer.

The above waxes have a melting point of 50 to 50.
Waxes having a temperature of 100 ° C., particularly about 60 to 90 ° C., are preferable, and examples thereof include beeswax, wooden wax, paraffin, crystallin wax, and oxidized wax. Examples of the natural resin include natural rubber and rosin. Further, examples of the fats and oils and modified products thereof include hardened oils, solid fatty acids, and metal salts thereof.

The alkaline substance blended in the coating layer in the present invention may be either an inorganic or organic compound which shows alkalinity in an aqueous solution, and is particularly solid at room temperature (average particle size of solid alkaline substance). Is 0.5-1
0 μm, especially 0.8 to 5 μm powder is preferable), and an alkaline substance that reacts gently with water is preferable, and examples thereof include alkaline earth metal carbonates and hydroxides.
Alternatively, an oxide, an inorganic compound such as an alkali metal carbonate, a phosphate, or a silicate, an organic acid salt of an alkali metal, and an organic compound such as an alkylamide can be given. Specific examples of the alkaline substance include calcium carbonate, calcium oxide, calcium hydroxide, magnesium carbonate, magnesium oxide, magnesium hydroxide, sodium carbonate, potassium carbonate, tripotassium phosphate, sodium silicate, and sodium acetate. Can be listed in.

In the coated granular fertilizer of the present invention, the blending amount (blending ratio) of the alkaline water-soluble polymeric substance contained in the coating layer is such that the polymeric material (alkaline water-soluble polymeric substance and water And the total amount of the polymer substances which are not soluble in alkaline water) 0.1 to 50
% By weight, in particular 0.2-30% by weight, and even
Amounts of 5 to 20% by weight are preferred.

In the present invention, if the blending amount of the alkaline water-soluble polymer substance is too small, the period until the fertilizer component is eluted from the coated granular fertilizer may be too long, and the blending amount may be too long. If the amount is too large, the elution of fertilizer components may become too fast.

In the coated granular fertilizer of the present invention, the use amount (blending amount) of the alkaline substance contained in the coating layer is
The amount of the alkaline water-soluble polymeric substance contained in the coating layer is 0.05 to 5 times by weight, particularly 0.1 to 3 times by weight, and further 0.1 to 1 times by weight. Is preferred. In the present invention, when the blending amount of the alkaline substance with respect to the blending amount of the alkaline water-soluble polymeric substance is small, the alkaline water-soluble polymeric substance is difficult to be sufficiently dissolved, and the elution start time of the fertilizer is too late, or the fertilizer. The elution rate of fertilizer after the start of elution tends to be too low.

Further, when the blending amount (blending ratio) of the alkaline substance with respect to the blending amount of the alkaline water-soluble polymer substance is increased, the elution rate of the fertilizer after the start of the elution of the fertilizer is increased, but it may be increased to a certain degree. However, the elution rate of fertilizer does not increase, and the content of fertilizer components in the coated granular fertilizer decreases relatively.

In the coated granular fertilizer of the present invention, the coating amount of the whole coating layer is 0.5 to 0.5 for each coated granular fertilizer.
The amount is preferably 30% by weight, particularly 1 to 20% by weight, more preferably 2 to 15% by weight (coverage). Further, in the coated granular fertilizer of the present invention, the total thickness of the coating layer is preferably about 30 to 300 μm, particularly about 50 to 150 μm.

The coated granular fertilizer of the present invention can be produced by various known coating methods for granular fertilizers.
While supplying hot air to form a fluidized bed (or spouted bed) of granular fertilizer, a coating material solution (spray liquid) is sprayed to adhere the coating material to the granular fertilizer, and the coating layer is dried to form granular particles. Method of coating fertilizer (fluidized bed method) or throwing granular fertilizer into a tilting plate type granulator, spraying a solution of coating material while blowing hot air to adhere coating material to granular fertilizer, and coating A method of drying the layer to coat the granular fertilizer can be mentioned.

The above-mentioned coated granular fertilizer is preferably produced by a fluidized bed coating method using, for example, a fluidized bed forming apparatus 1 as shown in FIG. In this fluidized bed forming apparatus 1,
A fertilizer particle supply hopper 2 and a granular fertilizer supply line 3 are connected to the upper part of the device. Further, a supply line 4 for the spray liquid a (a polymer solution in which a mixture of an alkaline water-soluble polymer substance and another polymer substance is dissolved) and a spray liquid b (a polymer that is insoluble in neither water nor alkaline water) A supply line 5 for a slurry solution in which a substance and an alkaline substance are dispersed) is connected to a spray liquid supply line 6 and a spray nozzle 7 where the supply lines join so that the flow paths can be switched by each valve. It is installed in the lower part of the device. A fluidized bed gas supply line 8 and its jet nozzle 9 are provided at the lower end of the apparatus, and an exhaust gas line 11 via a cooler 10 is further provided at the top of the apparatus. At the bottom of the device, the perforated plate 1
2 are provided.

In the coated granular fertilizer of the present invention, as described above, a multi-layered coating layer (for example, a polymer substance layer and an alkali substance-containing layer, the latter being an independent layer on the fertilizer particle side surface) is used. Independent constitution, a constitution in which a shielding layer made of a polymer substance that prevents permeation of an alkaline gas such as ammonia gas between the coating layer of the present invention and fertilizer particles is provided, and the surface of the coating layer of the present invention (Outer surface) may have a 2 to 4 layer structure such as a structure in which a protective layer made of a polymer substance or the like is provided). In the multilayer coated granular fertilizer according to the present invention, the thickness of the coating layer specified in the present invention is 20 to 80% or more of the total thickness of the coating layer, and particularly 30 to
It is preferably about 60%. In order to produce a coated granular fertilizer having these multiple coating layers, the above-mentioned coating operation is carried out using the same or different spray liquids 1 to 10 times,
Particularly, it may be repeated 1 to 5 times.

The solvent used when preparing the solution (spray solution) of the coating material used in the above-mentioned production method is
Hydrocarbon solvents such as aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons (including halogenated hydrocarbon solvents), ester solvents, ether solvents, alcohol solvents, ketone solvents, amide solvents Examples thereof include solvents or mixed solvents thereof.

Examples of the above-mentioned hydrocarbon solvents are aromatic hydrocarbon solvents such as benzene, toluene, xylene, methylnaphthalene, chlorobenzene, dichlorobenzene, petroleum ether, ligroin, n-hexane, methylene chloride, chloroform and dichloroethane. , Aliphatic hydrocarbon solvents such as trichloroethane, alicyclic hydrocarbon solvents such as cyclopentane and cyclohexane, and the like.

Examples of the above ether solvents include diethyl ether, tetrahydrofuran, dioxane, etc., and examples of the alcohol solvents include methanol, ethanol, propanol, butanol, isopropyl alcohol, etc., and ester solvents. Examples of the solvent include ethyl acetate, examples of the ketone solvent include methyl ethyl ketone, acetone, and methyl isobutyl ketone, and examples of the amide solvent include N,
Examples thereof include N-dimethylformamide and N, N-dimethylacetamide. In the production method of the present invention, as the solvent, a mixed solvent of 1 volume of aromatic hydrocarbon solvent and 0.1-10 volume of ketone solvent, particularly 0.5-5 volume is particularly preferable.

The mixing ratio of the polymer substance component contained in the spray liquid a (for example, the solution containing the alkaline water-soluble polymer substance and the other polymer substance) is not particularly limited. The concentration is preferably such that the composition can be supplied and sprayed as a spray liquid.
In particular, it is preferably 1 to 40% by weight, more preferably 2 to 20% by weight, and the mixing ratio of the alkaline substance (powder) contained in the spray liquid b (slurry solution of alkaline substance) is It is preferably about 1 to 40% by weight, especially 2 to 20% by weight. The spray liquid b may contain an appropriate other polymer substance in addition to the alkaline substance.

In the above manufacturing method, the coating temperature is 40 to
80 ° C., preferably about 40 to 70 ° C.,
In order to maintain the coating temperature, the gas for forming the fluidized bed is about 60-
It can be performed by heating to 100 ° C. and supplying. The fluidized bed forming gas is, for example, nitrogen gas,
An inert gas such as air may be used, and the supply amount of the gas for forming a fluidized bed may be the shape, size and amount of the granular fertilizer to be coated, the composition and amount of the spray liquids a and b to be sprayed, etc. Can be determined as appropriate.

The coated granular fertilizer obtained by the above-mentioned production method is preferably dried to a state in which it does not substantially contain the solvent used in the spray liquid or the like in the above-mentioned production method. It is preferable to continue supplying the fluidized bed forming gas for 1 to 30 minutes even after the supply is stopped.
The solvent contained in the coating layer formed on the coated granular fertilizer of the present invention is preferably about 1% by weight or less, and particularly preferably 0.1% by weight or less.

[0039]

EXAMPLES Next, reference examples relating to the preparation of the spray liquid used for forming the coating layer of the coated granular particles of the present invention, examples of the present invention, and comparative examples will be shown. Reference Example 1 Calcium hydroxide (manufactured by Hinomaru Industry Co., Ltd., slaked lime ultrafine powder grade, average particle size: about 5 μm) 1
0.4 kg, ethylene-vinyl acetate copolymer (Ube Industries, Ltd., trade name: VZ-289) 1.6 kg were dissolved in a mixed solvent of toluene 50% by weight and methyl ethyl ketone 50% by weight at 70 ° C. to give a solid. A first auxiliary coating layer forming liquid (spray liquid a: slurry liquid) having a content of about 10% by weight was prepared.

Reference Example 2 41.5 kg of an ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 18 mol% (hereinafter referred to as EEA resin, manufactured by Nippon Unicar Co., Ltd., trade name: NUC-6170), wax ( Nippon Seiro Co., Ltd., Microcrystalline wax, trade name: Hi-Mic-3090) 41.5 kg,
And a styrene-maleic anhydride copolymer (manufactured by ARCO Chemical Co., trade name: SMA resin-SMA1000)
10 kg was dissolved in a mixed solvent of 50% by weight of toluene and 50% by weight of methyl ethyl ketone at 80 ° C. to prepare a main coating layer forming liquid (spray liquid b: polymer solution) containing 8% by weight of solid content.

[Embodiment 1] In a fluidized bed forming apparatus (jet type) 1 having a tower diameter of 200 mm having a spray nozzle 7 for spray liquid as shown in FIG. 1 kg of 3 mm granular urea was introduced, and hot air (air for fluidized bed) at 80 ° C. was blown from the fluidized bed gas supply line 8 and its nozzle 9 to fluidize the granular urea 80
The first auxiliary coating layer forming liquid (spray liquid a) prepared in Reference Example 1 was heated at a temperature of 30 ° C., and was supplied at a supply rate of 30 cc / min via the supply line 4 (valve opened) and the supply line 6, and sprayed. The liquid a was sprayed from the spray nozzle 7 toward the fluidized granular urea for about 5 minutes to form a first auxiliary coating layer (thickness: 10 μm) on the granular urea at a coating temperature of about 80 ° C.

Subsequently, the temporary coated granular urea having the first auxiliary coating layer formed as described above was charged into the fluidized bed forming apparatus 1 to form a fluidized bed, and the main prepared in Reference Example 2 was used. The coating layer forming liquid (spray liquid b) is supplied at a supply rate of 100 cc / min via the supply line 5 (valve opened) and the supply line 6, and the spray liquid b is fluidized from the spray nozzle 7 to be temporarily coated granular urea. Forming a main coating layer on the first auxiliary coating layer of the temporary-coated granular urea in the same manner as the above-mentioned coating operation, except that the temporary-coated granular urea is further sprayed for about 15 minutes. A coated granular fertilizer A having a two-layer coating layer (thickness: 90 μm, and coating rate: 10.4% by weight) was produced.

In the above-mentioned granular urea coating operation, the temperature of the exhaust gas at the top of the fluidized bed forming apparatus 1 is set to 55 to 60.
C. was maintained. The obtained coated granular fertilizer contained 1.2 parts by weight of the first auxiliary coating layer and 10.4 parts by weight of the main coating layer per 100 parts by weight of urea, and contained the alkaline substance and the alkaline water-soluble polymer substance. The weight ratio (slaked lime / SMA resin) was 100/100.

Regarding the obtained coated granular fertilizer A, "Urea dissolution test method" [Fertilizer analysis method published by the Ministry of Agriculture, Forestry and Fisheries (Agricultural Environmental Technology Research Institute) (S62.12.25), 5.31 dissolution rate] According to this, the first dissolution test was carried out as it was. Table 1 shows the results. The obtained coated granular fertilizer A is heated to 50 ° C.
After storing it in a thermostatic bath for 36 days, take out the coated granular fertilizer (the storage in the thermostatic bath corresponds to having undergone the abuse test for 2 years) and perform the second dissolution test as described above. Then, the dissolution rate was measured. Table 1 shows the results. The respective dissolution curves obtained by these dissolution tests are shown in FIG. The results of the second dissolution test were not found to differ in characteristics from the results of the first dissolution test.

[0045]

[Table 1]

Reference Example 3 Instead of the styrene-maleic anhydride copolymer, an isobutylene maleic anhydride copolymer (Kuraray Co., Ltd., trade name: BM Polymer BM3) was used.
A main coating layer forming liquid (spray liquid b ′) was prepared in the same manner as in Reference Example 2 except that 0) was used.

[Comparative Example 1] The main coating layer forming liquid (spray liquid b ') prepared in Reference Example 3 was used in place of the main coating layer forming liquid (spray liquid b) prepared in Reference Example 2. A coating operation was performed in the same manner as in Example 1 to obtain a two-layer coating (thickness: 90 μm
m and the coverage rate: 10.3% by weight) coated granular fertilizer B
I got

With respect to the obtained coated granular fertilizer B, the first dissolution test was carried out as it was according to the above-mentioned "Urea dissolution test method". Table 2 shows the results. The obtained coated granular fertilizer B was stored at 50 ° C. for 36 days in a constant temperature bath, and then the coated granular fertilizer (the storage in the constant temperature bath corresponds to a two-year abuse test) was taken out. A second dissolution test was performed in the same manner as in, and the dissolution rate was measured. Table 2 shows the results. The dissolution curves obtained by these dissolution tests are shown in FIG. It was found that the results of the second elution test were faster in elution performance than the results of the first elution test.

[0049]

[Table 2]

Reference Example 4 Furthermore, an ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 18 mol% (the same EEA resin as in Reference Example 2) 50.0 k
g, wax (the same microcrystalline wax as in Reference Example 2) 83.0 kg, alkaline water-soluble rosin resin (manufactured by Arakawa Chemical Industry Co., Ltd., rosin modified maleic acid resin, trade name: Marquide No. 31) 23.3 kg, Also, 5.0 kg of calcium hydroxide (the same slaked lime ultrafine powder grade as in Reference Example 1) is dissolved in a mixed solvent of 50% by weight of toluene and 50% by weight of methyl ethyl ketone at 80 ° C., and a main coating containing 8% by weight of solid content. A layer forming liquid (spray liquid c: polymer-containing slurry solution) was prepared.

Example 2 2 kg of granular urea having an average particle diameter of 2.3 mm was charged from the granular fertilizer supply line 3 into the same fluidized bed forming apparatus (jet type) 1 as in Example 1, and hot air of 80 ° C. ( The fluidized bed air) is blown from the fluidized bed gas supply line 8 and its nozzle 9 to fluidize the granular urea and at the same time 80
Meanwhile, the coating layer forming liquid (spray liquid c) prepared in Reference Example 4 was supplied at a supply rate of 70 cc / min via the supply line 4 (valve opened) and the supply line 6 to prepare the spray liquid. c is sprayed from the spray nozzle 7 toward the fluidized granular urea for about 31 minutes to form a main coating layer (thickness: about 80 μm) on the granular urea at a coating temperature of about 80 ° C. Manufactured.

With respect to the obtained coated granular fertilizer C, the first dissolution test was carried out as it is according to the above-mentioned "Urea dissolution test method". Table 3 shows the results. 30 parts by weight of the obtained coated granular fertilizer C and 70 parts of advanced chemical fertilizer (manufactured by Ube Kasei Fertilizer, N: P: K = 7.5: 23.5: 23.5)
3 parts by weight and the mixed fertilizer at 50 ° C for 3
After being stored in a thermostat for 0 days, only the coated granular fertilizer C was selected and taken out, and the above-mentioned second dissolution test was performed to measure the dissolution rate. Table 4 shows the results.

In the second dissolution test, coated granular fertilizer C
Was mixed with advanced chemical fertilizer (prone to generate alkaline gas) and exposed to contact with basic gas at high temperature for a long time, but when it was not mixed with advanced chemical fertilizer at all (first In comparison with the elution test), no special difference was observed in the N component elution characteristics of any of the coated granular fertilizers in both test results.

[0054]

[Table 3]

[0055]

Industrial Applicability The coated granular fertilizer of the present invention has at least a coating material containing a special alkaline water-soluble polymer substance, a polymer substance insoluble in water or alkaline water, and an alkali substance on the surface of the fertilizer particles. Forming a coating layer that is blended, the coated granular fertilizer having this special coating layer is capable of adjusting the elution start time of the fertilizer component in a water-containing medium or water for a relatively long period, Moreover, this coated granular fertilizer has particularly good long-term storage stability.

[Brief description of the drawings]

FIG. 1 shows a fluidized bed forming apparatus (coating apparatus) that can be advantageously used for producing the coated granular fertilizer of the present invention.

FIG. 2 is a dissolution curve of a coated granular fertilizer A obtained in Example 1 in a dissolution test.

FIG. 3 is an elution curve of a coated granular fertilizer B obtained in Comparative Example 1 by an elution test.

FIG. 4 is an elution curve of a coated granular fertilizer C obtained in Example 2 by an elution test.

[Explanation of symbols]

 1 Fluidized Bed Forming Equipment 2 Granular Fertilizer Hopper 3 Granular Fertilizer Supply Line 4 Supply Line for Spray Liquid a 5 Supply Line for Spray Liquid b 6 Spray Liquid Supply Line 7 Spray Nozzle 8 Supply Line for Gas for Fluidized Bed 9 Gas for Fluidized Bed Supply nozzle 10 Exhaust gas cooler 11 Exhaust gas line 12 Perforated plate 13 Extraction line for coated fertilizer

Continuation of the front page (72) Inventor Kameura 10 1987, Kobegushi, Ube, Ube City, Yamaguchi Prefecture Ube Industries, Ltd.

Claims (8)

[Claims] 1. A fertilizer particle comprising at least a copolymer of a styrene monomer soluble in alkaline water and an unsaturated carboxylic acid or a derivative thereof, a polymer substance insoluble in water and alkaline water, and at least an alkaline substance. A coated granular fertilizer characterized by being coated with a coating layer containing three components as main components. 2. A first coating layer, wherein the coating layer is provided in contact with fertilizer particles containing an alkaline substance and a polymeric substance insoluble in both water and alkaline water as main components, and the first coating layer. As a main component, a copolymer of a styrene monomer soluble in alkaline water and an unsaturated carboxylic acid or its derivative provided as an independent layer outside the polymer and a polymeric substance insoluble in both water and alkaline water The coated granular fertilizer according to claim 1, comprising two layers of a second coating layer comprising. 3. The coated granular fertilizer according to claim 1, wherein the polymer substance insoluble in both water and alkaline water is an olefin polymer or copolymer. 4. A polymer in which the amount of a copolymer of a styrene monomer soluble in alkaline water and an unsaturated carboxylic acid or a derivative thereof is such that the copolymer or its derivative and water or alkaline water are insoluble. 0.1 to 5 of the total amount of substances
The coated granular fertilizer according to claim 1 or 2, wherein the amount of the alkaline substance is in the range of 0% by weight, and the amount of the alkaline substance is in the range of 0.05 to 5 times by weight the amount of the copolymer or its derivative. 5. Fertilizer particles are covered with a coating layer containing an alkaline water-soluble rosin resin, a polymeric substance insoluble in water and alkaline water, and at least three components of an alkaline substance as main components. A coated granular fertilizer characterized by the following. 6. The first coating layer, wherein the coating layer is provided in contact with fertilizer particles containing an alkaline substance and a polymer substance insoluble in both water and alkaline water as main components, and the first coating layer. 6. A second coating layer comprising, as a main component, an alkaline water-soluble rosin-based resin provided as an independent layer on the outer side of the composition and a polymeric substance insoluble in both water and alkaline water. The coated granular fertilizer described. 7. The coated granular fertilizer according to claim 5, wherein the polymer substance insoluble in both water and alkaline water is an olefin polymer or copolymer. 8. The amount of the rosin-based resin soluble in alkaline water is within the range of 0.1 to 50% by weight based on the total amount of the rosin-based resin and the polymeric substance insoluble in both water and alkaline water. The coated granular fertilizer according to claim 5 or 6, wherein the amount of the alkaline substance is within a range of 0.05 to 5 times by weight the amount of the rosin-based resin.