JPH10291881A - Coated granular fertilizer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adequately control the elution time and the elution rate of fertilizer components by coating the outside of the granular fertilizer with at least one layer of a coating film composed of a particle of a high water absorptive material having a specific particle diameter and an urethane resin. SOLUTION: This coated granular fertilizer is formed by coating the surface of the granular fertilizer with a coating film composed of the high water absorptive material having 1-200 μm particle diameter and the urethane resin and further coating with a coating film composed of the same or different urethane resin and containing no particle of the water absorptive material. The water absorptive material is selected from an acrylate based polymer, an isobutylene based polymer, a graft starch based polymer and the like and the quantity to be used is 1-50 wt.% of total of the urethane resin and the water absorptive material. The urethane resin is obtained by allowing a polyisocyanate or an isocyanate group-terminated prepolymer to react with a polyol such as caster oil or a caster oil derivative and an amine compound and the weight of the coating film occupies 1-30 wt.% of total weight of the coated granular fertilizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a granular fertilizer coated with a film having excellent water resistance and having a fertilizing effect controlling function.

[0002]

2. Description of the Related Art In recent years, fertilizers with more labor-saving and high fertilization efficiency and fertilization methods have been developed in view of the effects on the environment due to the runoff of fertilizer elution components of granular fertilizers and labor saving due to the aging of agricultural workers. Has been requested. Against this background,
Various fertilizer-controlling fertilizers have been proposed and put into practical use.

[0003] As one of such fertilizers, there is a coated fertilizer of a dissolution rate control type. This is a fertilizer in which the surface of the granular fertilizer is coated with an organic or inorganic coating material to control the elution of the internal fertilizer components. Among them, a coated fertilizer using an organic coating material such as a resin has a more excellent elution control function, and such a type occupies the mainstream of the coated fertilizer.

[0004] For example, a method of coating a copolymer of a cyclopentadiene oligomer and an unsaturated fatty acid oil as a coating material (Japanese Patent Publication No. 4-29410), reacting an oxypropylene adduct of ethylenediamine with an isocyanate compound. There has been proposed a method of forming a polyurethane coating layer (Japanese Patent Publication No. 54-39298).

Further, a premix containing an isocyanate component of an industrial diphenylmethane diisocyanate-based polyisocyanate equivalent to a polyol component comprising 30 parts of benzyl ether resin, 60 parts of castor oil and 10 parts of diacetone alcohol is applied to the granular fertilizer. Urethane-coated fertilizer cured with nitrogen saturated with dimethylamine at 20 ° C. as a catalyst,
No. 6648.

[0006] On the other hand, coated fertilizers have been developed which are intended to suppress the elution of fertilizer until a required time and to elute the fertilizer at a predetermined time according to the growth of the plant in a relatively short time. For example, JP-A-4-202079 discloses that a first coating layer is formed on a surface of a granular fertilizer (urea) with a highly water-swellable resin (crosslinked isobutylene polymer powder) together with polyethylene glycol as an adhesive. Then, a multilayer coated granular fertilizer having a second coating layer formed of an ethylene-ethyl acrylate copolymer is proposed, and it is disclosed that the elution start time is adjusted.

Japanese Patent Application Laid-Open No. 8-151286 discloses that a surface of a granular fertilizer is primarily coated with a wax, and the surface of the granular fertilizer is at least one selected from an alkyd resin and a substance soluble or swellable in water. A multi-layer coated granular fertilizer is described in which a primary coating material is melted or subjected to some treatment after being secondary coated with a material containing.

In Japanese Patent Application Laid-Open No. 4-202078, a first coating layer made of an alkaline substance is formed on the surface of a granular fertilizer, and an olefin polymer and an alkali water-soluble polymer are formed on the surface of the first coating layer. A coated granular fertilizer having a second coating layer formed of a mixture with the union is described, and it is disclosed that the timing of starting dissolution is adjusted.

In general, an organic solvent is often required in the process of producing a coated fertilizer using a resin or the like, and sufficient attention must be paid to toxicity, flammability, and the like during production. Incomplete removal of the organic solvent has an adverse effect on the environment, and removal and recovery of the solvent requires complicated operations and great expense.

[0010] Further, in the case of a coated fertilizer using a resin or the like, a resin coating remains in the soil after the fertilizer component is eluted, and its decomposition may take a considerably long time.

[0011]

DISCLOSURE OF THE INVENTION The present invention does not require the use of an organic solvent at the time of production, uses a naturally derived vegetable oil or fat as a raw material in consideration of biodegradability, and provides a uniform and water-resistant formed on a fertilizer. It is an object of the present invention to provide a coated granular fertilizer in which the elution time and the elution rate of a fertilizer component are appropriately adjusted by a coating having excellent properties.

[0012]

Means for Solving the Problems The present inventors have made intensive studies to solve the problems of the prior art, and found that a coating made of a urethane resin containing a powder of a highly water-absorbing substance was provided outside a water-soluble granular fertilizer. The formation of the fertilizer component and the elution speed of the fertilizer component were found to be appropriately controlled by the formation, and the present invention was reached.

[0013] That is, the present invention is a coated granular fertilizer in which the outside of the granular fertilizer is coated with at least one layer of urethane resin and particles of a superabsorbent material having a particle size of 1 to 200 µm. Here, the “outside” refers to a part outside the part including the part in contact with the surface of the granular fertilizer.

Although the urethane resin according to the present invention is not particularly limited as a polyol component, low molecular weight polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, diethylene glycol And diols such as dipropylene glycol, polyethylene glycol and polypropylene glycol, glycerin, trimethylol prepane, castor oil, castor oil derivatives and the like, and adducts thereof such as ethylene oxide and propylene oxide. Of these, the use of castor oil or castor oil derivatives is particularly preferred. Castor oil derivatives are castor oil partial hydrolysates, castor oil ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol And glycerin, trimethylolpropane, or a transesterified product with polyether polyol, or an esterified polyol of ricinoleic acid with the above-mentioned polyols. Among them, derivatives obtained by transesterifying castor oil with ethylene glycol or propylene glycol are preferably used.

In the present invention, these castor oil or castor oil derivatives have a viscosity at 25 ° C. of 1500 cps.
The following are preferably used from the viewpoint of workability during production and uniformity of the coating. The hydroxyl value is 10 to 400 mgKOH /
The range of g is preferable.If the hydroxyl value is smaller than this, the coating is too sticky and unsuitable because the coated fertilizer is agglomerated. Defects are likely to occur and sufficient fertility controllability cannot be obtained. Castor oil originally has a moderately high hydroxyl value (hydroxyl value = about 160 mg KOH / g) and a suitable viscosity (about 70 mg KOH / g).
0 cps), which is used as a suitable raw material for the present coated fertilizer.

The polyisocyanate according to the present invention is not particularly limited, but is preferably an aromatic polyisocyanate. Specifically, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (M
DI), naphthalene diisocyanate, polyphenyl polymethylene polyisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylene diisocyanate, etc., or modified products thereof.
For example, modified urea, dimer, trimer, carbodiimide, allohanate modified, buret modified and the like can be mentioned. These may be used in combination of two or more, and may be so-called "crude" polyisocyanates used industrially. MDI, crude MDI, carbodiimidated MDI (liquid MDI), T
DI, crude TDI and the like are particularly preferred.

The polyisocyanate according to the present invention is preferably used as an isocyanate group-terminated prepolymer prepared from the above polyisocyanate. The polyol used to prepare such an isocyanate-terminated prepolymer is the castor oil or castor oil derivative described above. The method for preparing the isocyanate group-terminated prepolymer may be a known method, and the equivalent ratio of NCO group / active hydrogen group between polyisocyanate and polyol is 1.1 to 50.0, preferably 1.2 to 50.0. 25.0, 30 to 130 ° C, preferably 40 to 90 ° C, 1 to 1
It is obtained by performing the reaction for 5 hours.

The isocyanate group-terminated prepolymer according to the present invention may be further modified. Such a modified product is obtained by adding a polyol to a polyisocyanate by NC.
The equivalent ratio of O group / active hydrogen group is 5.0 or more, preferably 8 to
25, more preferably 10 to 20 and not more than 15 mol% of all NCO groups of the polyisocyanate, preferably 2 to 1%.
A modified product containing a uretonimine and carbodiimide group obtained by using a polyol corresponding to 5 mol%, more preferably 4 to 9 mol%, and using a urethane bond and a catalyst. Such polyisocyanates include MDI,
Specifically, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate,
A single or arbitrary mixture of 2,4'-diphenylmethane diisocyanate or the like, a polyphenylpolymethylene polyisocyanate, or the like is used. As a catalyst for obtaining a modified product containing uretonimine and carbodiimide group of MDI, 3-methyl-1-phenyl-3-phospholene-1-oxide, 3-methyl-1-ethyl-3
-Phosphorene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide and the like. Such a catalyst is 1 to MDI.
A quantity of 300 ppm is used.

The modified product from such an isocyanate group-terminated prepolymer is prepared by reacting a polyisocyanate and a polyol at 30 to 130 ° C., preferably at 40 to 90 ° C. for 1 to 6 hours.
After reacting for an hour, an isocyanate group-terminated prepolymer is obtained.
To 130 ° C., preferably 60 to 90 ° C. for 3 to 5 hours, and the reaction is performed until the target NCO remaining amount is reached. Then, the reaction is stopped by adding a deactivator to remove the uretonimine and carbodiimide groups. A method for obtaining a modified product containing the polyisocyanate, or adding a polyol and a catalyst to a polyisocyanate, and adding a polyol and a catalyst at 30 to 130 ° C, preferably 60 to 90 ° C.
The reaction is carried out for up to 5 hours, and the reaction is stopped by adding an inactivating agent to obtain a modified product containing uretonimine and carbodiimide groups. As the deactivator,
Trichlorosilane, dichlorodiphenylsilane, trichloromonomethylsilane and the like are used. The amount of the deactivator to be used can be obtained by, for example, a method of adding 1 to 10 equivalents of the catalyst and stopping the reaction.

In such a reaction, a carbodiimide group (N = C = N) is first formed, but it is converted to uretonimine by standing at room temperature for a certain period of time. This reaction is a reversible reaction, and it is known that the uretonimine group dissociates into a carbodiimide group and an NCO group at a high temperature (usually 80 ° C. or higher).

Therefore, the ratio of carbodiimide group / uretonimine group is different, and when left at room temperature, it is almost present as uretonimine group. Those which can be used in the present invention may not be completely converted to uretonimine, and may partially contain a carbodiimide group. Conversely, those which are present in the form of carbodiimide groups when stored at high temperature, and those in which uretonimine is partially present can also be used. The amount of the uretonimine and carbodiimide modified product in the modified product of MDI was determined by MDI 100
20 to 60 parts by weight, preferably 30 to 5 parts by weight based on parts by weight
0 parts by weight. By using the MDI thus obtained as an isocyanate group-terminated prepolymer, the compatibility with other components becomes better than that of MDI alone, which promotes reactivity during use and improves viscosity in workability. There are effects such as adjusting to an easy-to-use one and improving adhesive strength.

As the amine compound according to the present invention, alkylamines or amine-based polyols are used. Examples of the alkylamine include trimethylamine, triethylamine, dimethylethylamine, dimethylisopropylamine and the like. The amine compound is preferably an amine-based polyol. Examples of such an amine-based polyol include low-molecular-weight amine-based polyols such as di-, tri-, ethanolamine and N-methyl-N, N'-diethanolamine. Or ethylenediamine,
Amino compounds such as 1,3-propanediamine, 1,6-hexanediamine and propylene oxide (PO)
Alternatively, it is an amine-based polyol to which an alkylene oxide such as ethylene oxide (EO) is added. The ratio of addition is not particularly limited, but is 1 to 200, preferably 1 to 50, alkylene oxides per nitrogen atom, but about 2 to 2.4 is preferred for controlling physical properties related to the hydrophilicity of the coating. Is particularly preferred. As such,
For example, N, N, N ', N'-tetrakis [2-hydroxypropyl] ethylenediamine, N, N, N', N '
-Tetrakis [2-hydroxyethyl] ethylenediamine, N, N, N ', N'-tetrakis [2-hydroxypropyl] -1,3-propanediamine, N, N,
N ', N'-tetrakis [2-hydroxyethyl]-
1,6-hexanediamine, N, N, N ′, N′-tetrakis [2-hydroxyethyl] ethylenediamine,
N, N, N ', N'-tetrakis [2-hydroxypropyl] -1,3-propanediamine, N, N, N',
N'-tetrakis [2-hydroxyethyl] -1,6-
Hexanediamine and the like can be mentioned. Particularly preferred are N, N, and N, because their reactivity and physical properties are improved.
N ', N'-tetrakis [2-hydroxypropyl] ethylenediamine and N, N, N', N'-tetrakis [2-hydroxyethyl] ethylenediamine or oxypropylene-modified ethylenediamine containing these as a main component, oxyethylenation Ethylenediamine.

In the present invention, when an amine-based polyol is used as the polyol component, it is preferably used because good compatibility with the resin composition is obtained and a uniform coating is easily formed. Amine polyol promotes the reaction and also acts as a crosslinking agent and chain extender,
Good curability and tough film properties are obtained.

The amount of the amine polyol is usually 0.01 to 30%, preferably 0.1 to 30% by weight of the urethane resin.
It is possible to adjust the curing speed by using in the range of 20%, more preferably 1１〜15%. If it is less than 0.01%, curing is insufficient and water resistance is poor, and sufficient fertility controllability cannot be obtained. On the other hand, if it exceeds 30%, the crosslinking reaction is too fast to form a uniform film, which is not preferable.

In the present invention, a catalyst may be further added to promote urethane bond formation, and an organic metal catalyst such as dibutyltin laurate and lead octenoate can be used.

It is preferable that the ratio of the hydroxyl group to the isocyanate group contained in the total amount of the polyol component and the isocyanate component used in the present invention is in the range of 0.5 to 2.0 as the ratio of hydroxyl group / isocyanate group. . If this ratio is less than 0.5 or more than 2.0, the resulting coating film is not sufficiently crosslinked, and the fertilizer dissolution rate is disadvantageously too high.

Further, in order to leave unreacted isocyanate groups in the resin film of the coated granular fertilizer and to impart flexibility to the film, the ratio of hydroxyl groups to isocyanate groups is defined as 1. 1-1.
The use in the range of 5 is also suitably adopted.

Further, the polyols used in the present invention,
In particular, a part of castor oil or castor oil derivatives is replaced with a vegetable oil or a modified vegetable oil having a conjugated double bond such as a conjugated diene, conjugated triene, or conjugated tetraene in the molecule, and the coating is formed by auxiliary crosslinking using a conjugated double bond. The flexibility and strength can also be adjusted and are preferably employed. Examples of vegetable oils or fats having a conjugated double bond include tung oil, dehydrated castor oil, conjugated soybean oil, conjugated linseed oil or a hydrolyzate thereof, transesterification with carboxylic acid or alcohol. Objects and the like.

The superabsorbent substance according to the present invention is a substance which swells to at least 5 times its dry volume by absorbing a large amount of water. In particular, a gel that does not show much solubility when absorbing water and is in a gel state is preferable. Specifically, for example, an acrylate polymer (for example, Sumikagel S, L, R manufactured by Sumitomo Chemical Co., Ltd.)
Type, Aqua Keep 10SH, 1 manufactured by Sumitomo Seika Co., Ltd.
0SHP, 10SH-NF (20), SA60NTYP
E2, Aquamate AQ-2 manufactured by Sekisui Plastics Co., Ltd.
00, AQ-200B-02, Sunfresh ST-500D, ST-500MP manufactured by Sanyo Chemical Industries, Ltd.
S), isobutylene-based polymer (for example, KI gel-201K, KI gel-201K-F2, K
I gel solution system, KI gel compound), acrylic acid / vinyl alcohol copolymer, polyethylene oxide modified resin, starch graft polymer (for example, Sunfresh ST-100, ST-5 manufactured by Sanyo Chemical Industries, Ltd.)
00S, ST-100MPS), starch (for example, potato starch, corn starch, sweet potato starch, soluble starch), carboxymethyl cellulose (CMC), CMC metal salt and bentonite. Of these, acrylate polymers, isobutylene polymers, and starch are particularly preferred.

The super absorbent material according to the present invention has a particle size of 1
To 200 μm, preferably 5 to 100 μm, and 20
７０70 μm is more preferred. When the particle size is less than 1 μm, the elution time due to the addition of the superabsorbent material compared to the resin without additives,
The change in the dissolution rate is too small, which is not effective for adjusting the dissolution characteristics. On the other hand, if the thickness exceeds 200 μm, a uniform urethane resin film cannot be formed, and the film tends to be defective, which is not preferable.

The amount of the superabsorbent substance to be added varies depending on the particle size, but is usually 1 to 50% by weight, preferably 2 to 20% by weight of the total weight of the urethane resin and the superabsorbent substance.
More preferably, it is 15% by weight. If the amount is less than 1% by weight, the change in the elution time and the elution rate due to the addition of the superabsorbent material is too small as compared with the non-added resin, and this is not effective for adjusting the elution characteristics. Also, 5
If it exceeds 0% by weight, the hydrophilicity increases and it becomes difficult to adjust the elution start time.

The coated granular fertilizer according to the present invention has a coating made of particles of a superabsorbent substance and a urethane resin on the outside of the granular fertilizer, and further has a coating different from the urethane resin on the inside or outside of the coating. be able to. The coating made of the particles of the superabsorbent material and the urethane resin may be a layer formed by applying the coating itself a plurality of times, or the coatings of the particles of the superabsorbent material and the urethane resin, and the coating of the superabsorbent material. It may have a plurality of coatings made of urethane resin containing no particles. Each urethane resin may have a different structure. The layer made of the urethane resin containing the particles of the superabsorbent substance and the layer made of the urethane resin not containing the particles may be laminated in any order. However, the outermost layer of the granular fertilizer is preferably a urethane resin that does not contain particles of the superabsorbent material.

[0033] A preferred layer structure of the coated granular fertilizer according to the present invention is, specifically, that the surface of the granular fertilizer has a particle size of 1 to 20.
0 μm particles of the superabsorbent material and a coating made of a urethane resin, and the outside thereof is covered with at least one layer of a coating containing no particles of the superabsorbent material made of the same or different urethane resin as the urethane resin. Coated granular fertilizer, the surface of the granular fertilizer is coated with a coating made of a urethane resin that does not contain particles of the superabsorbent substance, and the outside thereof has particles of the superabsorbent substance having a particle size of 1 to 200 μm and the urethane resin. And a coated granular fertilizer coated with at least one layer of urethane resin.

The weight of the film formed on the surface of the coated granular fertilizer of the present invention (the total weight of a plurality of layers) is as follows:
Usually 1-30% by weight of the weight of the coated granular fertilizer, 3
It is preferably from 20 to 20% by weight, more preferably from 3 to 15% by weight. The dissolution characteristics of the fertilizer component can be appropriately adjusted by the thickness of the coating.

The fertilizer coated in the present invention is not particularly limited as long as it is a granular fertilizer. Examples are urea,
Salt fertilizer, ammonium sulfate, ammonium nitrate, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, potassium phosphate, ammonium phosphate, phosphate lime, or composite fertilizers composed of two or more selected from these, and granular organic fertilizers, etc. Granular fertilizer.

As a supplementary means for improving workability at the time of coating and controlling the fertilizer effect, organic coatings other than the superabsorbent material may be added to the coating composition as long as the properties of the coating of the present invention are not substantially impaired. Alternatively, it is also possible to add an inorganic additive. Examples of the additive include alkyd resin, urethane resin, fatty acid ester, wax, rosin and derivatives thereof, ester gum, surfactant, petroleum resin, talc, diatomaceous earth, silica, urea, sulfur powder and the like.
These may be added in the range of 0.1 to 50 parts by weight based on 100 parts by weight of the urethane resin according to the present invention, and the workability or the elution characteristics of the fertilizer component may be adjusted by the type and amount of the addition. is there.

In the present invention, the method of coating the granular fertilizer is not particularly limited as long as it can be coated.
The components constituting the coating material may be independently added to the granular fertilizer, or some or all of the components may be mixed in advance and added to the granular fertilizer. The superabsorbent material is premixed with a polyol component with or without an amine-based polyol and dispersed to prepare a dispersion, which is added to the granular fertilizer immediately after mixing with the polyisocyanate component, or each is separately granulated. Preferably it is added to the fertilizer. Specifically, for example, by adding a coating material composed of a polyol component, a polyisocyanate component, a highly water-absorbing substance and an amine compound to granular fertilizer in a flowing or tumbling state and causing the fertilizer to adhere thereto, and heating it with hot air or the like. A method of forming a hardened film on the granular fertilizer can be adopted. A device such as a fluidized bed or a spouted bed can be used for fluidizing the granular fertilizer, and a device such as a rotating pan or a rotating drum can be used for rolling.

The method of adding the coating material is not particularly limited as long as it can be efficiently dispersed and added, and it can be carried out without being limited to spraying and dripping. For example, it is preferable to perform spraying addition using a two-fluid nozzle using compressed air. It is possible to form a simple coating.

In order to cure the coating, the coating is usually heated to room temperature (2.
The heating is performed at about 5 ° C.) to 150 ° C., preferably about 40 to 100 ° C., which is appropriately selected depending on the heating time, the composition ratio of the coating material, and the type of granular fertilizer. For example, in the case of a granular fertilizer containing a component which is easily decomposed or deteriorated by heat, it is necessary to coat at a relatively low temperature.
It is preferable to coat at the following temperature.

Although the coated granular fertilizer of the present invention is not clear, by retaining particles of the superabsorbent substance inside a urethane resin having water resistance, mechanical strength and flexibility, the initial elution rate of the particulate fertilizer can be reduced. It is inferred that contradictory characteristics of low and controlled dissolution rate after induction time were obtained. In addition, when using a urethane resin obtained using castor oil or a polyol component prepared from castor oil for most of the components and an isocyanate-terminated prepolymer, the urethane resin is prepared from a relatively simple composition. In spite of this, the urethane structure formed by making a part of the polyol component into an isocyanate group-terminated prepolymer in advance becomes complicated, and it seems that the structure becomes more complicated by incorporating a small amount of an amine-based polyol. It is. Although it is not clear, it is presumed that as a result, the contradictory properties of a better initial dissolution rate of the granular fertilizer and a controlled dissolution rate after the induction time had elapsed were obtained.

[0041]

The present invention will be described below with reference to examples. [Example 1] 800 g of urea having an average particle diameter of 3.3 mm was charged into a fluidized coating apparatus having a tower diameter of 10 cm, and 70 m from the bottom.
Hot air was fed at a flow rate of ³ / hr to keep the temperature at 80 ° C.

Next, 9.3 g of a superabsorbent substance (average particle size: 40 μm (catalog value: 20 to 50 μm, the same applies hereinafter)) of a crosslinked acrylate polymer: S manufactured by Sanyo Chemical Co., Ltd.
T-500MPS) in 35.3 g of castor oil (hydroxyl value = 160 mgKOH / g, viscosity (25 ° C.) = 700 cps) using a stirrer to disperse 41.9 g of a polyol component.
MDI-modified castor oil (isocyanate group-terminated prepolymer in which castor oil was mixed with an excess amount of MDI to make the weight of NCO groups 19% of the total weight), 6.5 g of propylene oxide adduct of ethylenediamine (propylene oxide / nitrogen Atomic ratio: 2 to 2.4, OH value: 760 m
gKOH / g) was sprayed through a mixer from a two-fluid nozzle from the top of the device into the device over 1 hour. After spraying,
After flowing at 70 ° C. for 2 hours, a film was formed on the urea fertilizer. This was cooled to room temperature to obtain the target coated granular fertilizer. The coverage is as follows: coverage (%) = (weight of coating / weight of coated granular fertilizer) × 1
It was represented by 00 and was 10% by weight.

Next, these coated fertilizer samples were subjected to a nitrogen (N) dissolution test. To measure the dissolution rate, put the coated granular fertilizer in a certain amount of water, leave it in a constant temperature bath at 25 ° C, take it out after a certain period, separate the fertilizer and the solution, and quantify the nitrogen content eluted in the water. Was. Table 1 shows the results.

[0044]

[Table 1]

Explanation of the table: Coverage (%) = (weight of coating / weight of coated granular fertilizer) ×
100-The particle diameter of the superabsorbent substance represents the average particle diameter on a volume basis, the unit is μm, and the amount is% by weight in the coating.

EDA-PO adduct: propylene oxide adduct of ethylenediamine. Acrylate: a crosslinked acrylic acid polymer. -Starch / acrylate: Crosslinked product of starch / acrylate copolymer.

Isobutylene / maleate: Crosslinked sodium salt of isobutylene / maleic anhydride copolymer [Example 2] As a coating material, 4.7 g of a highly water-absorbing substance (crosslinked acrylate polymer having an average particle size of 40 µm (20 to 50 µm) in advance: ST-500MP manufactured by Sanyo Chemical Co., Ltd.)
S) with 37.3 g of castor oil (hydroxyl value = 160 mg KOH /
g, viscosity (25 ° C.) = 700 cps), a polyol component dispersed using a stirrer, 44.1 g of MDI-modified castor oil (castor oil is mixed with an excess amount of MDI to reduce the weight of NCO groups to 19% of the total weight). Isocyanate group-terminated prepolymer.), 6.9 g of propylene oxide adduct of ethylenediamine (ratio of propylene oxide / nitrogen atom: 2 to 2.4, OH value: 760 mgKOH / g)
A coated granular fertilizer was produced using the same apparatus and application conditions as in Example 1 except that the used granular fertilizer was used. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 3 A crosslinked acrylate polymer having an average particle size of 60 μm (20 to 30 μm) (Aquakeep 10SH manufactured by Sumitomo Seika Co., Ltd.) was used as a super-water-absorbing substance as a coating material.
A coated granular fertilizer was produced under the same apparatus and application conditions as in Example 2 except that 4.7 g of -NF) was used to obtain a coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 4 A crosslinked acrylate polymer having an average particle size of 17 μm (10 μm or less) (Aqualic CA-ML manufactured by Nippon Shokubai Co., Ltd.) was used as a super-water-absorbing material as a coating material.
Except that 4.7 g of 10) was used, a coated granular fertilizer was produced under the same apparatus and application conditions as in Example 2 to obtain a coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 5 The same apparatus and application conditions as in Example 1 were used except that 9.3 g of potato starch having an average particle size of 70 μm (literature value: 10 to 90 μm) was used as a super-water-absorbing substance as a coating material. The production of coated granular fertilizer was carried out at to obtain coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 6 A crosslinked product of a starch / acrylate copolymer having an average particle size of 40 μm (20 to 50 μm) (ST-ST manufactured by Sanyo Kasei Kogyo Co., Ltd.)
A coated granular fertilizer was produced using the same apparatus and application conditions as in Example 2 except that 4.7 g of 100 MPS) was used to obtain a coated granular fertilizer. Example 1 shows the dissolution rate of the obtained coated granular fertilizer.
The results are shown in Table 1.

Example 7 A crosslinked product of an isobutylene-maleic anhydride copolymer Na salt having an average particle diameter of 20 μm (200 mesh pass) (KI gel-210K manufactured by Kuraray Co., Ltd.) Except that 4.7 g of F2) was used, a coated granular fertilizer was produced under the same apparatus and application conditions as in Example 2 to obtain a coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 8 As a coating material, 4.7 was used in advance.
g of superabsorbent substance (average particle diameter 40 μm (20 to 50 μm)
m) Crosslinked acrylate polymer: ST manufactured by Sanyo Chemical Industries, Ltd.
-500 MPS) to 64.0 g of castor oil (hydroxyl value =
160 mg KOH / g, viscosity (25 ° C.) = 700 cps) The same apparatus as in Example 2 except that a polyol component dispersed using a stirrer, 22.0 g of crude MDI, and 1.0 of triethanolamine were used. The coated granular fertilizer was manufactured under the above conditions and the application conditions to obtain the coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1. [Example 9] As an amine-based polyol as a coating material, ethylene glycol castor oil fatty acid ester (monoester of a fatty acid obtained by hydrolyzing castor oil and ethylene glycol, OH value: 160 mgKOH / g, viscosity (25 ° C):
A coated granular fertilizer was produced under the same apparatus and application conditions as in Example 2 except that 37.3 g of 220 cps) was used to obtain a coated granular fertilizer. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

Example 10 A drum type rolling coating apparatus having a diameter of 30 cm was charged with 800 g of urea having an average particle diameter of 3.3 mm, and hot air was fed at a rate of 70 m ³ / hr to the apparatus and kept at 80 ° C. did.

Next, 9.3 g of a superabsorbent substance (average particle size of 40 μm
35.3 g of castor oil (hydroxyl value = 160 mgKOH / g, viscosity (25 ° C.) = 70) of (20-50 μm) crosslinked acrylate polymer: ST-500MPS manufactured by Sanyo Chemical Industries, Ltd.
0 cps) using a stirrer to disperse the polyol component, 41.9 g of MDI-modified castor oil (castor oil is mixed with excess MDI to reduce the weight of NCO groups to 19% of the total weight).
Isocyanate group-terminated prepolymer. ), 6.5
g of propylene oxide adduct of ethylenediamine (ratio of propylene oxide / nitrogen atom: 2 to 2.4,
OH number: 760 mg KOH / g)
The liquid was sprayed from the fluid nozzle into the apparatus over 1 hour. After spraying, tumbling was performed at 70 ° C. for 2 hours to form a film on the urea fertilizer. This was cooled to room temperature to obtain the target coated granular fertilizer, and the elution rate of the nitrogen component was measured. Table 1 shows the results.

Example 11 800 g of urea having an average particle diameter of 3.3 mm was charged into a fluidized coating apparatus having a tower diameter of 10 cm.
Hot air was sent from the lower part at a flow rate of 70 m ³ / hr to flow and maintained at 80 ° C.

Next, 2.4 g of a highly water-absorbing substance (a crosslinked acrylate polymer having an average particle size of 40 μm (20 to 50 μm): ST-500MPS manufactured by Sanyo Chemical Co., Ltd.)
6 g of castor oil (hydroxyl value = 160 mg KOH / g, viscosity (2
(5 ° C.) = 700 cps) A polyol component dispersed using a stirrer, 22.0 g of MDI-modified castor oil (castor oil was mixed with an excess amount of MDI to make the weight of NCO groups 19% of the total weight isocyanate-terminated. Prepolymer.) 3.5 g of propylene oxide adduct of ethylenediamine (ratio of propylene oxide / nitrogen atom:
2-2.4, OH value: 760 mgKOH / g) from a two-fluid nozzle through a mixer into the apparatus from the top of the apparatus.
Spraying was performed over time to form a film containing particles of the superabsorbent material.

Next, using the same raw materials, castor oil 1
9.6 g, 23.3 g of MDI-modified castor oil, and 3.6 g of a propylene oxide adduct of ethylenediamine were sprayed from a two-fluid nozzle through a mixer from above into the apparatus over 1 hour. After spraying, the mixture was allowed to flow at 70 ° C. for 2 hours to form a coating containing no superabsorbent particles outside the urea fertilizer. This was cooled to room temperature to obtain a coated granular fertilizer having a two-layer coating of a coating containing a superabsorbent substance and a coating containing no superabsorbent substance in this order from the inside. The dissolution rate of the obtained coated granular fertilizer was measured. Table 1 shows the results.

Example 12 800 g of urea having an average particle diameter of 3.3 mm was charged into a fluidized coating apparatus having a tower diameter of 10 cm.
Hot air was sent from the lower part at a flow rate of 70 m ³ / hr to flow and maintained at 80 ° C.

Next, 2.4 g of a superabsorbent substance (crosslinked acrylate polymer having an average particle size of 40 μm (20 to 50 μm): ST-500MPS manufactured by Sanyo Chemical Co., Ltd.)
1 g of castor oil (hydroxyl value = 160 mg KOH / g, viscosity (2
(5 ° C.) = 700 cps) Polyol component dispersed with a stirrer using an agitator, 22.1 g of crude MDI-modified castor oil (castor oil mixed with excess MDI to make the weight of NCO groups 20% of the total weight of isocyanate groups) Terminal prepolymer.) 3.9 g of propylene oxide adduct of ethylenediamine (propylene oxide / nitrogen atom ratio: 2 to 2.4, OH value: 760 mg KOH / g) was passed through a mixer from a two-fluid nozzle to the top of the apparatus. Was sprayed into the apparatus for 1 hour to form a film containing particles of the superabsorbent material.

Next, using the same raw materials, castor oil 1
9.0 g, crude MDI-modified castor oil 23.4 g, and propylene oxide adduct of ethylenediamine 4.1 g were sprayed from a two-fluid nozzle through a mixer from above into the apparatus over 1 hour. After spraying, flow at 70 ° C for 2 hours,
A coating was formed outside the urea fertilizer. This was cooled to room temperature to obtain a coated granular fertilizer having a two-layer coating of a coating containing a superabsorbent substance and a coating containing no superabsorbent substance in this order from the inside. The dissolution rate of the obtained coated granular fertilizer was measured. Table 1 shows the results.

[Comparative Examples 1 and 2] The superabsorbent resin was not used, and the coverage was 10% by weight (Comparative Example 1) or 5% by weight.
Example 1 by adjusting the coating weight so as to obtain (Comparative Example 2)
Was tested. The dissolution rate of the obtained coated granular fertilizer was measured. Table 1 shows the results.

Comparative Example 3 A crosslinked acrylate polymer having an average particle size of 380 μm (200 to 300 μm) (Aqua Keep 1 manufactured by Sumitomo Seika Co., Ltd.)
OSH) was used, and the coated granular fertilizer was produced using the same apparatus and application conditions as in Example 2 except that 4.7 g of the coated granular fertilizer was used. The coverage was 10% by weight. The dissolution rate of the obtained coated granular fertilizer was measured in accordance with Example 1, and the results are shown in Table 1.

[0064]

As is clear from the results of the examples, the coated granular fertilizer of the present invention achieved a low initial dissolution rate of the fertilizer and a controlled dissolution rate after the elapse of the induction time. Also,
The production of the coated granular fertilizer of the present invention can be performed without using an organic solvent.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Shioda 2805 Imafukunakadai, Kawagoe-shi, Saitama Central Research Institute of Chemical Research Co., Ltd. (72) Inventor Kentaro Tsutsumi 2805 Imafukunakadai, Kawagoe-shi, Saitama Central Glass Inside the Chemical Laboratory Co., Ltd.

Claims (17)

[Claims] 1. A coated granular fertilizer in which the outside of the granular fertilizer is coated with at least one layer of a urethane resin and particles of a superabsorbent substance having a particle size of 1 to 200 μm. 2. The coated granular fertilizer according to claim 1, wherein the surface of the granular fertilizer is coated with at least one layer of a urethane resin and particles of a superabsorbent substance having a particle size of 1 to 200 μm. 3. The surface of the granular fertilizer is coated with a coating made of a urethane resin and particles of a superabsorbent substance having a particle size of 1 to 200 μm, and the outside thereof is made of at least a urethane resin which is the same as or different from the urethane resin. The coated granular fertilizer according to claim 1, wherein the coated granular fertilizer is coated with one layer of a coating containing no particles of the superabsorbent material. 4. The surface of a granular fertilizer is coated with a coating made of a urethane resin containing no particles of a superabsorbent substance, and the outside thereof is coated with particles of a superabsorbent substance having a particle size of 1 to 200 μm and the urethane resin. The coated granular fertilizer according to claim 1, wherein at least one layer of the same or different urethane resin is coated. 5. The coated granular fertilizer according to claim 1, wherein the urethane resin is a polyurethane resin obtained by curing an aromatic polyisocyanate and a castor oil or a castor oil derivative polyol with an amine compound. 6. An isocyanate group-terminated prepolymer in which the urethane resin is obtained from (a) an aromatic polyisocyanate and castor oil or castor oil derivative polyol,
The coated granular fertilizer according to claim 1, which is a polyurethane resin obtained by curing with (b) castor oil or a castor oil derivative polyol and (c) an amine-based polyol. 7. The isocyanate group-terminated prepolymer having an isocyanate group / hydroxy group ratio of 1.1 to 50.0 in the aromatic polyisocyanate and castor oil or castor oil derivative polyol. Coated granular fertilizer. 8. The coated granular fertilizer according to claim 1, wherein the aromatic polyisocyanate is diphenylmethane diisocyanate, crude diphenylmethane diisocyanate or carbodiimidated diphenylmethane diisocyanate. 9. The coated granular fertilizer according to claim 1, wherein the castor oil derivative polyol is a transesterified product of castor oil and ethylene glycol or propylene glycol. 10. The isocyanate group-terminated prepolymer,
The coated granular fertilizer according to claim 1, which is a modified carbodiimide group-containing modified product obtained by reacting an aromatic polyisocyanate with a castor oil or a castor oil derivative polyol with an excess of isocyanate groups and modifying the prepolymer obtained by adding a catalyst. 11. An amine polyol comprising N, N, N ',
N'-tetrakis [2-hydroxypropyl] ethylenediamine or N, N, N ', N'-tetrakis [2-
The coated granular fertilizer according to claim 1, which is [hydroxyethyl] ethylenediamine. 12. The coated granular fertilizer according to claim 1, wherein the superabsorbent substance is an acrylate polymer, an isobutylene polymer, a graft starch polymer or starch. 13. The coated granular fertilizer according to claim 1, wherein the superabsorbent is 1 to 50% by weight of the total weight of the urethane resin and the superabsorbent. 14. The granular fertilizer comprises urea, ammonium salt, ammonium sulfate, ammonium nitrate,
The coated granular fertilizer according to claim 1, which is a composite fertilizer comprising at least two selected from potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, potassium phosphate, ammonia phosphate, lime phosphate, or an organic fertilizer. 15. A granular fertilizer in a flowing state or a rolling state, comprising an aromatic polyisocyanate and a particle size of 1 to 200 μm.
A method for producing a coated granular fertilizer, comprising applying a castor oil or a castor oil derivative polyol containing a particle of a superabsorbent substance and a polyol component comprising an amine compound, and curing and coating a polyurethane resin film. 16. A granular fertilizer in a fluidized state or a tumbled state, comprising: (a) an isocyanate group-terminated prepolymer obtained from aromatic polyisocyanate and castor oil or castor oil derivative polyol; and high water absorption having a particle size of 1 to 200 μm. The coated granular fertilizer according to claim 15, comprising applying a polyol component comprising (b) castor oil or a castor oil derivative polyol and (c) an amine-based polyol containing particles of an active substance, curing and coating with a polyurethane resin film. Production method. 17. The method for producing a coated granular fertilizer according to claim 15, wherein the granular fertilizer is a granular fertilizer having a coating made of a urethane resin containing or not containing particles of a superabsorbent substance.