JP2010120785A - Coated granular fertilizer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide coated granular fertilizer coated with a urethane resin derived from castor oil and having high water resistance, and to which suitable collapsibility is imparted by the addition of a highly water-absorbable resin, in which the elution season and elution speed of fertilizer components are more suitably adjustable, and, jointly, to provide coated granular fertilizer which has high coating biodegradability and high biological oxygen demand (BOD), and is environment-friendly. <P>SOLUTION: Regarding the coated granular fertilizer in which the outer part of granular fertilizer is coated with a coating of at least one layer comprising the grains of a highly water-absorbable substance with a grain size of 1 to 100 μm, a urethane resin and a wax, the wax is a petroleum wax having a melting point of 40 to 100°C, and the mass of the wax is preferably 10 to 45% of the whole mass of the coating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

   The present invention relates to a granular fertilizer having a fertilization effect adjusting function coated with a coating having excellent water resistance.

   In recent years, fertilizers with higher labor efficiency and fertilization efficiency and their application methods have been demanded from the viewpoints of environmental impact due to the runoff of fertilizer elution components of granular fertilizers, labor saving with the aging of agricultural workers, etc. . Based on such a background, various fertilizers with adjustable fertilizers have been proposed and put into practical use.

  This is a fertilizer in which the elution of internal fertilizer components is controlled by coating the surface of the granular fertilizer with an organic or inorganic coating material. Among them, coated fertilizers using organic coating materials such as resins have a better elution control function, and such a type occupies the mainstream of coated fertilizers.

  Various types of resins are used, but urethane resins are widely used for reasons such as coating strength, high water resistance, ease of control of elution characteristics, and the ability to be applied without the use of solvents. ing. Urethane resin is a cured resin with a three-dimensional structure and forms a very strong and strong water-resistant coating. On the other hand, it is a film that is necessary for coated granular fertilizers that are less likely to disintegrate by water and elute fertilizer early. The thickness is reduced and the uniformity is problematic. In response to this, the elution timing and elution rate of fertilizer components are adjusted appropriately by adding highly water-absorbing resins such as acrylate polymers, starch, and isobutylene / maleate polymers to urethane resins. This is described in Patent Document 1.

On the other hand, Patent Document 2 (Japanese Patent Laid-Open No. 2000-44377) describes that the elution time can be delayed by adding a wax to a urethane resin as well known in other resins. .
In addition, with coated fertilizers using resins, etc., the resin film remains in the soil after elution of the fertilizer components, and it takes a considerable amount of time to decompose, and the biochemical oxygen demand (BOD) is low. May put a load on the environment.
Japanese Patent Laid-Open No. 10-291881 JP 2000-44377 A

  The present invention is a urethane-coated granular fertilizer coated with a highly water-resistant urethane resin imparted with moderate disintegration by adding a highly water-absorbent resin with high water resistance. An object of the present invention is to provide a coated granular fertilizer that can appropriately adjust the elution characteristics. In addition, it aims to provide an environmentally friendly coated granular fertilizer because the biodegradability of the coating is high and the biochemical oxygen demand (BOD) is high.

  The present inventors have examined the elution characteristics necessary for appropriately adjusting the elution time and elution rate of the fertilizer components for the coated granular fertilizer coated with the urethane resin containing the fine particles of the superabsorbent resin. In spite of being used for the purpose of delaying the elution time in urethane resin coatings in the past, granular fertilizer coated with urethane resin manufactured from specific components and urethane resin with high water absorption resin added with specific wax Surprisingly, the inventors have found that an elution pattern in which the elution rate is appropriately adjusted can be set without delaying the elution time, and the present invention has been completed.

  Conventionally, as disclosed in JP-A-2000-44377, JP-A-2003-104787, etc., waxes that are hydrophobic substances are added to urethane resins for the purpose of delaying elution of fertilizers, or multilayers. It has been used for some layers of coatings. The granular fertilizer coated with urethane resin is considered to cause the depolymerization of urethane when urethane resin comes into contact with water, causing the coating to collapse, and the internal fertilizer to elute to the outside. It was speculated that if hydrophobicity was imparted, the contact between the urethane resin and water was hindered, the coating was prevented from collapsing, and the elution time was delayed.

However, in the present invention, in a specific urethane resin composition, by adding a wax that is a hydrophobic substance, an elution pattern in which the elution time is shortened and the elution rate is appropriately adjusted can be achieved.
[1] The outer part of the granular fertilizer is a coated granular fertilizer coated with at least one layer of a film comprising a superabsorbent material having a particle diameter of 1 to 200 μm, a urethane resin and a wax, and the wax has a melting point of 40 Coated granular fertilizer that is petroleum wax at -100 ° C, and the mass of the wax is 10-45% of the total mass of the coating.
[2] The coated granular fertilizer according to [1], wherein the wax is paraffin wax.
[3] The coated granular fertilizer according to [1] or [2], which is further coated with at least one layer of film not containing particles of the superabsorbent resin.
[4] The coated granular fertilizer according to [1] to [3], which is further coated with at least one layer of a coating film not containing wax.
[5] The coated granular fertilizer according to [1] to [4], wherein the urethane resin is a urethane resin obtained by curing aromatic polyisocyanate and castor oil or castor oil derivative polyol with an amine compound.
[6] The coated granular fertilizer according to [1] to [5], wherein the outermost layer is a coating containing no wax.
[7] A compound fertilizer in which the granular fertilizer is urea, ammonium sulfate, ammonium sulfate, ammonium nitrate, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, potassium phosphate, ammonia phosphate, lime phosphate or two or more selected from these, Or the coated granular fertilizer of [1]-[6] which is an organic fertilizer.
[8] A granular fertilizer in a fluidized state or a rolling state; (a) an isocyanate group-terminated prepolymer obtained from an aromatic polyisocyanate and castor oil or castor oil derivative polyol; and (b) a high particle size of 1 to 200 μm. The coated granular fertilizer according to any one of [1] to [7], wherein a polyol component comprising castor oil or castor oil derivative polyol, amine-based polyol and wax containing particles of water-absorbing substance is applied, cured and coated with a urethane resin coating. Production method.
[9] The method for producing a coated granular fertilizer according to [8], wherein the polyol component and the granular fertilizer are applied at a temperature equal to or higher than the melting point of the wax, cured, and coated with a urethane resin coating.

  Here, “external” means a part other than the granular fertilizer, including a part in contact with the surface of the granular fertilizer in the coated granular fertilizer.

  The coated granular fertilizer of the present invention is an environmentally-friendly coated granular fertilizer having a high biochemical oxygen demand (BOD), but the wax is added to a coating composed mainly of a urethane resin and a superabsorbent resin, thereby reducing the wax. A sigmoid (S-shaped) elution pattern can be set without delaying the elution time of the fertilizer as compared with a conventional film not added.

  The coated granular fertilizer of the present invention is a coated granular fertilizer coated with at least one layer of a film comprising a superabsorbent material having a particle diameter of 1 to 200 μm, a urethane resin and a wax. As the wax, petroleum wax is particularly preferable.

  The coated granular fertilizer according to the present invention has a coating containing a urethane resin on the outside of the granular fertilizer, but the coating may be a uniform layer or a plurality of layers. The thickness may be different. In the present specification, the entire portion other than the fertilizer formed outside the granular fertilizer is referred to as a coating, but each layer composed of a plurality of layers may also be referred to as a coating. In the case where the coated fertilizer formed by coating urethane resin on the fertilizer particles has a coating composed of a plurality of layers, the coating composed of the superabsorbent particles having a particle diameter of 1 to 200 μm according to the present invention, the urethane resin and the wax. The outermost layer, the innermost layer (the layer in contact with the fertilizer surface), or any other intermediate layer may be used. At that time, as the component constitution of the other layer than the superabsorbent material particles having a particle size of 1 to 200 μm, and at least one layer of a film made of urethane resin and wax, particles of the superabsorbent material having a particle size of 1 to 200 μm are used. And a layer made of urethane resin, a layer made of urethane resin and wax, a layer made of urethane resin not containing superabsorbent resin, or a layer made only of wax. Of these, other resins can be used instead of the urethane resin layer containing neither the superabsorbent resin nor the wax, for example, urethane resins derived from polyols other than castor oil, polyethylene or alkyd Resins such as resins can also be used.

  The film thickness of the superabsorbent material having a particle diameter of 1 to 200 μm according to the present invention, the film made of urethane resin and wax, and the thickness of the other layer are not particularly limited, but are adjusted to be 1 to 50 μm. It is preferably ˜25 μm. If it is less than 1 μm, the number of times of coating increases, which is not preferable because it is inefficient in operation. When the film thickness exceeds 50 μm, the viscosity of the uncured urethane resin is increased during the coating operation, and the particles adhere to each other and are coated as agglomerated particles. That is not preferable.

  The coated granular fertilizer of the present invention can include a plurality of coatings composed of the respective components described above, and the total film thickness is 20 to 200 μm. However, for fertilizer particles of about 1 to 5 mm, the coated granular fertilizer is usually coated granular. It is 1-30 mass% of the mass of a fertilizer, it is preferable that it is 3-20 mass%, and it is more preferable that it is 3-15 mass%. The elution characteristics of the fertilizer component can be appropriately adjusted depending on the thickness of the coating.

  Examples of the polyol component of the urethane resin according to the present invention include castor oil, castor oil derivatives and the like, or adducts of alkylene oxides such as ethylene oxide or propylene oxide. Castor oil derivatives include castor oil partial hydrolyzate, castor oil ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol Diols such as glycerin, trimethylol prepane, or a transesterified product with a polyether polyol, or esterified polyols with ricinoleic acid and the aforementioned polyols. Among these, a derivative obtained by transesterifying castor oil with ethylene glycol or propylene glycol is preferably used.

  In the present invention, among these castor oils or castor oil derivatives, those having a viscosity at 25 ° C. of 1500 mPa · s or less are preferably used from the viewpoint of workability during production and uniformity of the coating. Further, those having a hydroxyl value in the range of 10 to 400 mgKOH / g are preferable, and when the hydroxyl value is smaller than this, the coating is too sticky and the coated fertilizer is agglomerated, which is inappropriate. When the hydroxyl value is large, defects are likely to occur in the coating, and sufficient fertilization effect controllability cannot be obtained. Castor oil originally has a moderately high hydroxyl value (hydroxyl value = about 160 mg KOH / g) and an appropriate viscosity (about 700 mPa · s), and is used as a suitable raw material for the present coated fertilizer.

  The polyisocyanate according to the present invention is not particularly limited, but an aromatic polyisocyanate is preferable. Specifically, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, polyphenyl polymethylene polyisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate, etc., or modified products thereof, for example , Urea-modified products, dimers, trimers, carbodiimide products, allophanate-modified products, and burette-modified products. These may be used in combination of two or more, and may be so-called “crude” polyisocyanates used industrially. Of the above, MDI, crude MDI, carbodiimidized MDI (liquid MDI), TDI, crude TDI and the like are particularly preferable.

  Moreover, it is preferable to use the polyisocyanate concerning this invention as an isocyanate group terminal prepolymer prepared from said polyisocyanate. The polyol used to prepare such an isocyanate group-terminated prepolymer is castor oil or castor oil derivative as described above. The method for preparing the isocyanate group-terminated prepolymer may be a known method, wherein the equivalent ratio of NCO group / active hydrogen group of polyisocyanate and polyol is 1.1 to 50.0, preferably 1.2 to As 25.0, it is obtained by carrying out the reaction at 30 to 130 ° C., preferably 40 to 90 ° C. for 1 to 5 hours.

  The isocyanate group-terminated prepolymer according to the present invention may be further modified. Such a modified product has an NCO group / active hydrogen group equivalent ratio of 5.0 or more, preferably 8 to 25, more preferably 10 to 20, and 15 mol% of all NCO groups of the polyisocyanate. Hereinafter, it is a modified body containing a uretonimine and a carbodiimide group obtained by using a polyol corresponding to 2 to 15 mol%, more preferably 4 to 9 mol%, more preferably using a urethane bond and a catalyst. Examples of such polyisocyanates include MDI, specifically 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, etc., alone or in any mixture, or polyphenylpolymethylene polymethylene. Isocyanate or the like is used. As catalysts for obtaining modified products containing uretonimine and carbodiimide groups of MDI, 3-methyl-1-phenyl-3-phospholene-1-oxide, 3-methyl-1-ethyl-3-phospholene-1-oxide And phospholene-based catalysts such as 3-methyl-1-phenyl-2-phospholene-1-oxide. Such catalysts use an amount of 1 to 300 ppm based on MDI.

  A modified product from such an isocyanate group-terminated prepolymer is obtained by reacting a polyisocyanate and a polyol at 30 to 130 ° C., preferably 40 to 90 ° C. for 1 to 6 hours, to obtain an isocyanate group-terminated prepolymer, A catalyst is added to the prepolymer, the reaction is performed at 30 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. In addition, the reaction is stopped to obtain a modified product containing uretonimine and carbodiimide groups, or a polyol and a catalyst are added to polyisocyanate, and the reaction is carried out at 30 to 130 ° C., preferably 60 to 90 ° C. for 3 to 5 hours. Is obtained by adding a deactivator to stop the reaction 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 used can be obtained by adding an amount corresponding to 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 into uretonimine by leaving it at room temperature for a certain period of time. This reaction is a reversible reaction, and it is known that a uretonimine group dissociates into a carbodiimide group and an NCO group at a high temperature (usually 80 ° C. or higher).

  Therefore, the abundance ratio of carbodiimide group / uretonimine group is different, and it is almost present as a uretonimine group when left at room temperature. What can be used in the present invention may not be completely converted to uretonimine, and may partially contain a carbodiimide group. Conversely, those that exist in the form of a carbodiimide group during high-temperature storage, and those that partially contain uretonimine can also be used. The amount of the uretonimine and the carbodiimide modified product in the modified product of MDI is 20 to 60 parts by mass, preferably 30 to 50 parts by mass with respect to 100 parts by mass of MDI. By using the MDI thus obtained as an isocyanate group-terminated prepolymer, the compatibility with other components becomes better than that of MDI alone, promoting the reactivity during use and improving the viscosity. There are effects such as adjusting to an easy one and improving the 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 amine-based polyols include low-molecular amine polyols such as di-, tri-, ethanolamine, N-methyl-N, N'-diethanolamine. Or an amine-based polyol obtained by adding an alkylene oxide such as propylene oxide (PO) or ethylene oxide (EO) to an amino compound such as ethylenediamine, 1,3-propanediamine, or 1,6-hexanediamine. Although the ratio of addition is not particularly limited, alkylene oxide is 1 to 200, preferably 1 to 50 per nitrogen atom, but about 2 to 2.4 is used for adjusting physical properties related to hydrophilicity of the film. 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 and the like can be mentioned. Particularly preferred are N, N, N ′, N′-tetrakis [2-hydroxypropyl] ethylenediamine and N, N, N ′, N′-tetrakis [2 because of their good reactivity and physical properties. -Hydroxyethyl] ethylenediamine or oxypropylenated ethylenediamine or oxyethylenated ethylenediamine based on them.

  In the present invention, when an amine-based polyol is used as the polyol component, good compatibility with the resin composition is obtained, and a uniform film is easily formed. The amine-based polyol promotes the reaction and also acts as a crosslinking agent and a chain extender, and good curability and tough film properties can be obtained.

  The amount of amine polyol used is usually 0.01 to 30%, preferably 0.1 to 20%, more preferably 1 to 15% of the urethane resin mass, and the curing rate can be adjusted. It is. If it is less than 0.01%, the curing is insufficient and the 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 and a uniform film cannot be formed, which is not preferable.

In the present invention, a catalyst may be further added to promote urethane bond formation, and organometallic catalysts such as dibutyltin laurate and lead octenoate can be used.
The ratio of hydroxyl group and isocyanate group contained in the total amount of polyol component and isocyanate component used in the present invention is preferably in the range of 0.5 to 2.0 as the ratio of hydroxyl group / isocyanate group. When this ratio is less than 0.5 or more than 2.0, the resulting coating is not sufficiently crosslinked, and the disadvantage is that the elution rate of the fertilizer is too high.

  Furthermore, for the purpose of leaving unreacted isocyanate groups in the resin coating of the coated granular fertilizer and imparting flexibility to the coating, the ratio of hydroxyl group to isocyanate group is 1.1 to 1 as the ratio of hydroxy group / isocyanate group. It is also preferably used in the range of .5.

  In addition, a part of castor oil or castor oil derivative is replaced with vegetable oil or modified vegetable oil having a conjugated double bond such as conjugated diene, conjugated triene, or conjugated tetraene in the molecule, and is coated with auxiliary crosslinking by conjugated double bond. It is also possible to adjust the flexibility and strength, and it is preferably employed. Examples of vegetable fats and oils having a conjugated double bond or modified vegetable oils include tung oil, dehydrated castor oil, conjugated soybean oil, conjugated linseed oil, or their hydrolysates, carboxylic acids or alcohols. Thing etc. are mentioned.

  The superabsorbent substance according to the present invention is a substance that swells to 5 times or more of the dry volume by absorbing a large amount of water. Particularly preferred is a gel that does not show much solubility during water absorption. Specifically, for example, an acrylate polymer (for example, Sumikagel S, L, R type manufactured by Sumitomo Chemical Co., Ltd., Aqua Keep 10SH, 10SHP, 10SH-NF (20) manufactured by Sumitomo Seika Co., Ltd.) , SA60NTYPE2, Aqua Mate AQ-200, AQ-200B-02, Sanyo Chemical Industries, Ltd. Sunfresh ST-250MPS, ST-500MPSA) manufactured by Sekisui Plastics Co., Ltd., isobutylene polymer (for example, Kuraray KI Gel-201K, KI Gel-201K-F2, KI Gel Solution System, KI Gel Compound), acrylic acid / vinyl alcohol copolymer, polyethylene oxide-modified resin, starch graft polymer, starch (for example, , Potato starch, corn starch, sweet potato starch, soluble starch), carboxymethyl cellulose (CMC), include CMC metal salt and bentonite. Among these, an acrylate polymer, an isobutylene polymer, and starch are preferable, and an acrylate polymer is particularly preferable.

  The particle size of the superabsorbent material according to the present invention is 1 to 200 μm, preferably 5 to 100 μm, and more preferably 20 to 70 μm. If it is less than 1 μm, the change in the elution time and elution rate due to the addition of the superabsorbent substance is too small compared to the additive-free resin, and this is not effective for adjusting the elution characteristics. On the other hand, if it exceeds 200 μm, a urethane resin film with good uniformity cannot be formed, and defects are likely to occur in the film.

  The amount of the superabsorbent substance to be added varies depending on the particle size, but is usually 1 to 50 mass%, preferably 2 to 20 mass%, and 3 to 15 mass% of the total mass of the urethane resin and the superabsorbent material. More preferably. If it is less than 1% by mass, the change in the elution time and elution rate due to the addition of the superabsorbent material is too small compared to the additive-free resin, and this is not effective for adjusting the elution characteristics. Moreover, when it exceeds 50 mass%, hydrophilicity will become large and adjustment of the elution start time will become difficult.

  The type of the wax is determined by the compatibility between the wax and the resin, the bondability, the penetration into the gap, the water resistance of the wax itself, and the fertilizer elution characteristics by the combination of the wax and the superabsorbent resin. As the wax, petroleum wax, polyolefin wax, modified wax having aromatic group, hydrocarbon compound having alicyclic group, natural wax, long chain fatty acid having 12 or more carbon atoms or ester thereof are used. Of these, petroleum waxes are preferred because petroleum wax does not cause a delay in the elution time and the elution rate of the elution pattern can be adjusted appropriately, and paraffin wax is particularly preferred.

  Petroleum waxes include paraffin wax, microcrystalline wax (microwax), beeswax, carnauba wax, montan wax and the like. Paraffin wax is a petroleum wax having a melting point of 40 to 80 ° C. that is solid at room temperature mainly composed of linear hydrocarbons separated and purified from vacuum distillation distillate, and microcrystalline wax is mainly taken from the vacuum distillation residue of crude oil. It is a petroleum wax that contains a large amount of branched hydrocarbons and saturated alicyclic hydrocarbons, has a higher molecular weight than paraffin wax, and has a solid melting point of 60 to 100 ° C. at room temperature.

  Examples of the polyolefin wax include low molecular weight polypropylene, low molecular weight polyethylene, oxidized polypropylene, oxidized polyethylene, and the like. Specific examples of polyolefin waxes include, for example, Hoechst Wax PE520, Hoechst Wax PE130, Hoechst Wax PE190 (manufactured by Hoechst), Mitsui High Wax 200, Mitsui High Wax 210, Mitsui High Wax 210M, Mitsui High Wax 220, Mitsui High Wax Non-oxidized polyethylene wax such as 220M (Mitsui Petrochemical Industries), Sun Wax 131-P, Sun Wax 151-P, Sun Wax 161-P (Sanyo Chemical Industries), Hoechst Wax PED121, Hoechst Wax PED153, Hoechst Wax PED521, Hoechst Wax PED522, Ceridust 3620, Ceridust VP130, Ceridust VP5905, Ceridust VP9615A, Ceridust TM9610F, Ceridust3715 (manufactured by Hoechst), Mitsui Oils & Chemicals 420M ) Oxidized polyethylene wax such as Sun Wax E-300, Sun Wax E-250P (Sanyo Kasei Kogyo Co., Ltd.), Hoechis t Non-oxidized polypropylene wax such as Wachs PP230 (Hoechst), Biscol 330-P, Biscol 550-P, Biscol 660P (Sanyo Chemical Industries), and Biscol TS-200 (Sanyo Chemical Industries, Ltd.) Oxidized polypropylene wax, such as

  As the wax, those having a softening point in the range of 40 ° C. to 150 ° C., preferably those having a softening point in the range of 50 ° C. to 110 ° C. are used. When the softening point is 40 ° C. or lower, the wax melts during outdoor storage and the like, and the elution performance is impaired, and solidification may occur. When the softening point is 150 ° C. or higher, a high temperature is required to be mixed into the urethane resin at the time of coating formation, so that the stability of the resin is hindered, and the thickness is inhibited by heat shrinkage, etc. It becomes difficult to get things.

  Among these, petroleum wax is preferable because it is excellent in dispersibility in polyol, and paraffin wax is more preferable. Among the petroleum waxes, those having a melting point of 40 to 100 ° C. are preferred.

  Among paraffin waxes, those having a melting point of 40 to 70 ° C are particularly preferable, and those having a melting point of 50 to 60 ° C are more preferable. Paraffin wax having a melting point of 40 to 70 ° C. is preferable because it has excellent dispersibility in polyols, and the resulting film has high strength and an elution pattern of a sigmoid type.

  The effect of the wax is that when the polyol component and the polyisocyanate component react, the non-reactive component wax acts as a kind of void, and the original three-dimensional structure of the urethane resin becomes sparse, and water penetrates into the void. It is presumed that it becomes easier to cause the water resistance of the urethane resin to change. Further, the elution pattern of the fertilizer can also be controlled by changing the size and density of the voids depending on the addition rate of wax and the type of wax.

  In the case where the coated granular fertilizer has a single layer or a plurality of coatings, the amount of wax added is preferably in the range of 0.001 to 80% by mass, and preferably 0.001 to 60% by mass of the mass of each layer added with wax. 0.001 to 50% by mass is more preferable. If it is less than 0.001% by mass, the effect of mixing the wax is not sufficient, and if it exceeds 80% by mass, the viscosity increases remarkably in the mixed state of the urethane resin component and the wax at the time of film formation, making it difficult to form a uniform film. It is not preferable.

  In addition, when the coated granular fertilizer has a single layer or a plurality of coatings, the amount of wax added is in the range of 0.001 to 45% by mass of the entire coating including a layer to which no wax is added, The range of 10-45 mass% is preferable, and 15-45 mass% is more preferable. If the amount is less than 45% by mass, the elution of the fertilizer component can be adjusted by adjusting the amount of wax added. However, if the amount exceeds 45% by mass, a uniform and tough film cannot be formed and the elution pattern is changed to a sigmoid type. Since it is difficult to do, it is not preferable.

The coated granular fertilizer according to the present invention has a coating composed of particles of a superabsorbent material having a particle diameter of 1 to 200 μm, a urethane resin and a wax outside the granular fertilizer, and further the urethane resin inside or outside the coating. It can have a coating of different components than the coating composition. The coating composed of particles of the superabsorbent material, the urethane resin and the wax may be a layer formed by a plurality of coatings, and the coating composed of particles of the superabsorbent material, the urethane resin and the wax, You may have the several film which consists of the urethane resin which does not contain the particle | grains or wax of a water absorbing substance. Each urethane resin coating composition may have a different chemical structure. The film made of the highly water-absorbing substance, the coating made of urethane resin and wax, and the layer made of the urethane resin not containing particles or wax of the highly water-absorbing substance may be laminated in any order.
Specifically, the preferred layer structure of the coated granular fertilizer according to the present invention is specifically as follows: (1) The surface of the granular fertilizer is coated with a film made of a superabsorbent material having a particle diameter of 1 to 200 μm, a urethane resin and a wax. And a coated granular fertilizer coated with a coating containing at least one layer of a superabsorbent material which is the same or different from the urethane resin, and (2) the surface of the granular fertilizer is waxed It is coated with a coating made of a superabsorbent material and a urethane resin that does not contain, and at least one layer comprising a superabsorbent material particle having a particle diameter of 1 to 200 μm and a urethane resin that is the same as or different from the urethane resin. (3) The surface of the granular fertilizer is coated with a coating made of a urethane resin that does not contain particles of a superabsorbent material, and the exterior And a coated granular fertilizer coated with at least one layer of a film of a superabsorbent material having a particle diameter of 1 to 200 μm and a urethane resin and wax that is the same as or different from the urethane resin. However, it is preferable that the outermost layer of the granular fertilizer is a coating film that does not contain either the particles of the superabsorbent material or the wax or a urethane resin that does not contain the wax.

  The fertilizer covered in this invention will not be specifically limited if it is a granular fertilizer. Examples thereof include urea, ammonium sulfate, ammonium sulfate, ammonium nitrate, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, potassium phosphate, ammonia phosphate, lime phosphate, or a composite fertilizer composed of two or more selected from these, and Normal granular fertilizers, such as a granular organic fertilizer, are mentioned.

Further, as long as the properties of the coating film of the present invention are not substantially impaired, as a supplementary means for improving workability and controlling fertilization effect during coating, in addition to the superabsorbent material, the coating material composition may be organic or inorganic. It is also possible to add other additives. Examples of the additive include alkyd resin, urethane resin, fatty acid ester, rosin and derivatives thereof, ester gum, surfactant, petroleum resin, talc, diatomaceous earth, silica, urea, sulfur powder and the like. It is also possible to add these in the range of 0.1 to 50 parts by mass with respect to 100 parts by mass of the urethane resin according to the present invention, and to adjust the workability or the elution characteristics of the fertilizer component according to these types and addition amounts. is there.
In the present invention, the method for coating the coating on the granular fertilizer is not particularly limited as long as it can be coated, but it is only necessary to add a component constituting the coating material to the granular fertilizer in a fluidized state. Each of them may be independently added to the granular fertilizer and mixed in the coating apparatus, or a part or all of the components may be mixed in advance and added to the granular fertilizer. The superabsorbent material is premixed and dispersed with a polyol component containing or not containing an amine-based polyol, and a dispersion is prepared and added to the granular fertilizer immediately after mixing with the polyisocyanate component, or separately. Can be added to the granular fertilizer inside. The wax can be added alone, but it is preferable to add it as a uniform liquid by premixing with the polyisocyanate component. Specifically, for example, a coating material composed of a polyol component containing wax, a polyisocyanate component, a superabsorbent material and an amine compound is added to and adhered to a granular fertilizer in a fluidized or rolling state, and this is heated with hot air or the like. A method of forming a cured film on the surface of the granular fertilizer by heating can be employed. An apparatus such as a fluidized bed or a spouted bed can be used for fluidizing the granular fertilizer, and an apparatus such as a rotating pan or a rotating drum can be used for rolling.

  The wax is preferably mixed with a polyol component in advance and used as a dispersion because it is easy to handle. Since the polyol component and the wax do not dissolve, a dispersion is prepared by mixing and stirring at a temperature equal to or higher than the melting point of the wax. This temperature is 0 to 50 ° C. higher than the melting point, preferably 0 to 30 ° C., more preferably 0 to 10 ° C. If this temperature is less than 0 ° C., the wax is solid or semi-solid, so that a dispersion cannot be prepared substantially. If it exceeds 50 ° C., the polyol component is decomposed and the viscosity is increased, which makes the coating operation difficult. Is not preferable. The temperature at the time of preparation and the temperature of the granular fertilizer at the time of application are preferably substantially the same, but different temperatures can be used, and the preparation temperature can be higher than the temperature of the granular fertilizer. The dispersion may be stored and used after preparation, but is preferably used immediately after adjustment, and if possible, it is preferably performed immediately before spraying into the coating apparatus.

  The method of adding the coating material is not particularly limited as long as it can be dispersed and added efficiently, and can be carried out without being limited to spraying and dropping. For example, a good film can be formed by spraying with a two-fluid nozzle using compressed air. It is possible to form.

  In order to harden the coating, heating is usually performed at room temperature (about 25 ° C.) to 150 ° C., preferably about 40 to 100 ° C., but it 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 granular fertilizer containing components that are easily decomposed or altered by heat, it is necessary to coat at a relatively low temperature, and in the case of urea, it is preferable to coat at a temperature of 90 ° C. or less. Moreover, although heating time changes with heating temperature, the kind of catalyst, and quantity, Usually, it is 1 minute-2 hours for every layer, 2 minutes-1 hour are preferable, and 3-30 minutes are more preferable. If it is less than 1 minute, it will harden | cure rapidly and it will be difficult to apply | coat a uniform film | membrane, and if it exceeds 2 hours, productivity will fall and it is unpreferable.

  In the coated granular fertilizer of the present invention, the outermost layer surface can be treated with an inorganic powder for the purpose of preventing mutual sticking between fertilizer particles. Examples of the inorganic powder include talc, sulfur, calcium carbonate, silica, zeolite, diatomaceous earth, clay, and metal oxide, and these can be used alone or in combination. Of these, talc is easy to handle. Therefore, it is preferable.

  The inorganic powder is preferably used in an amount of 1 to 15% by mass, more preferably 3 to 10% by mass, based on the resin. If it is less than 1% by mass, the effect of preventing sticking is weak, and even if it exceeds 15% by mass, it does not adhere to the surface of the coated granular fertilizer, which is useless. In addition, it is preferable that the inorganic powder is sprayed on the granular fertilizer that is in a rolling or fluidized state as it is after the addition of a urethane raw material such as a polyol component in the coating process. Further, the inorganic powder is preferably sprayed after the urethanization reaction is completed and the resin is cured and in a state having adhesive force. In this way, since the inorganic powder stays on the surface and does not enter the resin, the elution is also stabilized.

Hereinafter, the present invention will be described by way of examples.
[Example 1]
1,000 g of granular urea (particle size 2.5 to 4.0 mm) was charged in a drum type rolling coating apparatus having a diameter of 30 cm, and the granular urea temperature was maintained at 65 ° C. by a hot air generator while rolling at 30 rpm. Next, a polyol component obtained by mixing 3.5 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle size of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 37.6 g of castor oil (hydroxyl value 160 mgKOH / g) 6.8 g of propylene oxide adduct of ethylenediamine (propylene oxide / nitrogen atom ratio; 2.2, hydroxyl value; 760 mgKOH / g) and 23.0 g of paraffin wax (Nippon Seiwa Co., Ltd., product name 135, melting point 58) And 44.2 g of MDI modified castor oil heated to 65 ° C. (isocyanate group-terminated prepolymer in which castor oil is mixed with an excess amount of MDI so that the mass of NCO groups is 19% of the total mass). It sprayed (application | coating) over 1 hour in the apparatus from the two fluid nozzle. After spraying, the film was rolled at 65 ° C. for 30 minutes to form a film on the granular urea. This was cooled to room temperature (about 30 ° C.) to obtain the desired coated granular fertilizer. Next, these coated granular fertilizers were reduced and subjected to measurement of coverage ((coated mass / coated granular fertilizer mass) × 100), nitrogen elution test, and BOD measurement. The coverage was 10.0%. In the dissolution test, a certain amount (10 g) of the reduced coated fertilizer is sampled and put into a predetermined amount (200 cc) of ion-exchanged water, stored in a constant temperature bath at 25 ° C., taken out after a predetermined time, and put into water. The eluted nitrogen content was determined quantitatively. The results are shown in FIG.

  On the other hand, for the BOD measurement, a hole was drilled with a needle in 10 g of the coated fertilizer that had been shrunk, and the fertilizer components were eluted in 1,000 cc of ion exchange water, and then the elution shell was air-dried. 0.5 g of this elution shell was pulverized to 0.1 to 0.5 mm with a mixer and subjected to BOD measurement. The BOD measurement was based on JISK6950, using BOD seeds (Cyblon Chemicals, USA) as a seeding source with 0.05 g of the ground sample, a culture temperature of 30 ° C., and a culture period of 20 days. The results are shown in Table 1 and FIG.

[Examples 2 to 5, Comparative Examples 1 to 3]
The coated granular material was the same as in Example 1 except that the superabsorbent resin, castor oil, propylene oxide adduct of ethylenediamine, paraffin wax, and MDI modified castor oil used in Example 1 were changed to the amounts shown in the table. Fertilizer production and properties were measured. The results are shown in Table 1 and FIG. Comparative Example 1 is a standard case where no wax is added and is a sigmoid type, but the BOB is small and biodegradation cannot be expected. In Comparative Examples 2 and 3, the amount of paraffin wax added was 50% and 60%, respectively, and the elution characteristics deviated from the sigmoid type.

[Example 6]
1,000 g of granular urea (particle size 2.5 to 4.0 mm) was charged in a drum type rolling coating apparatus having a diameter of 30 cm, and the granular urea temperature was maintained at 65 ° C. by a hot air generator while rolling at 30 rpm. Next, a polyol component obtained by mixing 0.5 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle size of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 4.3 g of castor oil (hydroxyl value 160 mgKOH / g) And propylene oxide adduct of 0.8 g of ethylenediamine (propylene oxide / nitrogen atom ratio: 2.2, hydroxyl value: 760 mgKOH / g) and 5.8 g of paraffin wax (Nippon Seiwa Co., Ltd., product name 135, melting point 58) C) and 5.1 g of MDI modified castor oil heated to 65 ° C. (isocyanate group-terminated prepolymer in which castor oil was mixed with an excess amount of MDI to make the mass of NCO groups 19% of the total mass). Spray from the two-fluid nozzle into the apparatus for 1 minute. After spraying, it was rolled for 9 minutes at 65 ° C. Further, the coating operation was performed 6 times. After the final spraying, the film was rolled for 30 minutes at 65 ° C. to form a film on the granular urea. This was cooled to room temperature (about 30 ° C.) to obtain the desired coated granular fertilizer. Next, these coated granular fertilizers were reduced and subjected to measurement of coverage ((coated mass / coated granular fertilizer mass) × 100), nitrogen elution test, and BOD measurement. The coverage was 10.1%. The dissolution test and BOD measurement were performed in the same manner as in Example 1. The BOD value is 0.36 g / g-film, and the dissolution results are shown in FIG.

[Example 7]
1,000 g of granular urea (particle size 2.5 to 4.0 mm) was charged in a drum type rolling coating apparatus having a diameter of 30 cm, and the granular urea temperature was maintained at 65 ° C. by a hot air generator while rolling at 30 rpm. Next, a polyol component obtained by mixing 1.8 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle size of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 14.0 g of castor oil (hydroxyl value 160 mgKOH / g). And 2.5 g of ethylenediamine propylene oxide adduct (propylene oxide / nitrogen atom ratio; 2.2, hydroxyl value; 760 mgKOH / g) and 23.0 g of paraffin wax (Nippon Seiwa Co., Ltd., product name 115, melting point 48 16.3 g of MDI modified castor oil heated to 65 ° C. (an isocyanate group-terminated prepolymer in which castor oil is mixed with an excess amount of MDI to make the mass of NCO groups 19% of the total mass). Spraying from the two-fluid nozzle into the apparatus took 30 minutes. Subsequently, a polyol component obtained by mixing 1.8 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle size of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 23.9 g of castor oil (hydroxyl value 160 mgKOH / g). 27.5 g of MDI heated to 65 ° C. with a mixture of 65 ° C. and propylene oxide adduct of 4.3 g ethylenediamine (propylene oxide / nitrogen atom ratio; 2.2, hydroxyl value: 760 mgKOH / g) at 65 ° C. Modified castor oil (an isocyanate group-terminated prepolymer in which castor oil was mixed with an excess amount of MDI so that the mass of NCO groups was 19% of the total mass) was sprayed into the apparatus from a two-fluid nozzle over 30 minutes. After spraying, it was rolled at 65 ° C. for 30 minutes. This was cooled to room temperature (about 30 ° C.) to obtain the desired coated granular fertilizer. Next, these coated granular fertilizers were reduced and subjected to measurement of coverage ((coated mass / coated granular fertilizer mass) × 100), nitrogen elution test, and BOD measurement. The coverage was 9.9%. The dissolution test and BOD measurement were performed in the same manner as in Example 1. The BOD value is 0.22 g / g-film, and the dissolution results are shown in FIG.

[Example 8]
1,000 g of granular urea (particle diameter: 2.5 to 4.0 mm) was charged into a drum type rolling coating apparatus having a diameter of 30 cm, and the granular urea temperature was maintained at 75 ° C. with a hot air generator while rolling at 30 rpm. Next, a polyol component obtained by mixing 0.6 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle diameter of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 4.7 g of castor oil (hydroxyl value 160 mgKOH / g). At 75 ° C., 0.8 g of ethylenediamine propylene oxide adduct (propylene oxide / nitrogen atom ratio; 2.2, hydroxyl value: 760 mg KOH / g) and 7.7 g of paraffin wax (LUVAX-1266, made by Nippon Seiwa) 69 ° C.) and 5.4 g of MDI modified castor oil heated to 75 ° C. (isocyanate group-terminated prepolymer in which castor oil is mixed with an excess amount of MDI to make the mass of NCO groups 19% of the total mass) Was sprayed into the apparatus from a two-fluid nozzle for 1 minute. After spraying, it was rolled for 9 minutes at 72 ° C. Further, the coating operation was performed twice. Subsequently, 0.6 g of a superabsorbent resin (cross-linked acrylate polymer having an average particle size of 25 μm; ST-500MPSA manufactured by Sanyo Chemical Industries) and 7.9 g of castor oil (hydroxyl value 160 mgKOH / g) polyol component and 1 0.5 g of ethylenediamine propylene oxide adduct (ratio of propylene oxide / nitrogen atom; 2.2, hydroxyl value; 760 mg KOH / g) and 9.2 g of MDI modified castor oil (castor oil) heated to 75 ° C. An isocyanate group-terminated prepolymer mixed with an excess amount of MDI and having a mass of NCO groups of 19% of the total mass) was sprayed into the apparatus from a two-fluid nozzle for 1 minute. After spraying, it was rolled for 9 minutes at 75 ° C. Further, the coating operation was performed twice. After the final spraying, the film was rolled at 75 ° C. for 30 minutes to form a film on the granular urea. This was cooled to room temperature (about 30 ° C.) to obtain the desired coated granular fertilizer. Next, these coated granular fertilizers were reduced and subjected to measurement of coverage ((coated mass / coated granular fertilizer mass) × 100), nitrogen elution test, and BOD measurement. The coverage was 10.0%. The dissolution test and BOD measurement were performed in the same manner as in Example 1. The BOD value is 0.21 g / g-film, and the dissolution results are shown in FIG.

[Comparative Examples 4 to 6]
As wax, urethane type wax (Nippon Seiwa product name NPS-6010 melting point 74 ° C.), oxidized wax (Nippon Seiwa product name OX-020T melting point 100 ° C.), synthetic wax (Nippon Seiwa product name FNP-0115 melting point 115 ° C.) ) Was used to produce a coated fertilizer in the same manner as in Example 3, and the same test was performed. The results are shown in Table 2.

  Preparation of a mixed liquid (coating material B) composed of a superabsorbent resin, castor oil, propylene oxide adduct of ethylenediamine and wax was performed at a temperature 5 ° C. higher than the melting point of each wax, and the coating material B maintained at that temperature was used. The coated fertilizer was produced by applying to a granular fertilizer at 90 ° C. and curing at that temperature. In the dissolution test of the obtained coated fertilizer, the initial dissolution could not be suppressed and the sigmoid-type dissolution pattern was not achieved.

It is a diagram which shows the elution rate in each elution day about the samples of Examples 1-5 and Comparative Examples 1-3. It is a diagram which shows the elution rate in each elution day about the sample of Examples 6-8.

Claims (4)

The outside of the granular fertilizer is a coated granular fertilizer coated with at least one layer of a coating film comprising a superabsorbent particle having a particle diameter of 1 to 200 μm, a urethane resin and a wax, and the wax has a melting point of 40 to 100 ° C. A coated granular fertilizer having a wax mass of 10 to 45% of the total mass of the coating. The coated granular fertilizer according to [1], wherein the wax is paraffin wax. The coated granular fertilizer according to claim 1 or 2, wherein the urethane resin is a urethane resin obtained by curing aromatic polyisocyanate and castor oil or castor oil derivative polyol with an amine compound. (A) an isocyanate group-terminated prepolymer obtained from aromatic polyisocyanate and castor oil or castor oil derivative polyol; and (b) a superabsorbent material having a particle size of 1 to 200 μm. A coated granule according to any one of claims 1 to 3, which comprises applying a polyol component comprising castor oil or castor oil derivative polyol, an amine-based polyol and a wax, and curing and coating with a urethane resin film. Fertilizer manufacturing method.