JP2001163691A - Coated granular fertilizer and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated fertilizer, elution of which is accurately regulated, and to obtain its manufacturing method. SOLUTION: Fertilizing effect adjusting type coated granular fertilizer, which is coated with a coating material consisting essentially of a carnauba wax and a polyurethane resin produced by a reaction of an oil modified alkyd resin and diphenylmethane diisocyanate and/or tolylenediisocyanate, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated granular fertilizer in which elution of a fertilizer is controlled with high precision and a method for producing the same. More specifically, the present invention relates to a fertilizer-controllable coated granular fertilizer coated with a coating material comprising a specific thermosetting resin and a specific wax.
More specifically, a coating material containing carnauba wax and a polyurethane resin produced by the reaction of an oil-modified alkyd resin with diphenylmethane diisocyanate (hereinafter referred to as MDI) and / or tolylene diisocyanate (hereinafter referred to as TDI). The present invention relates to a coated fertilizer with a controlled fertilizer effect.

[0002]

2. Description of the Related Art In recent years, due to environmental problems such as eutrophication of enclosed water areas and contamination of groundwater by nitrate nitrogen, reduction of environmental load such as reduction of fertilizer has become an issue. In addition, labor-saving fertilizers are required due to the declining agricultural population, and some crops require only a small amount of nutrient supply during the early stage of growth and require an appropriate amount of nutrient during the growing season. There is a demand for fertilizers that can suppress the elution of fertilizers at the initial stage and supply a proper amount of nutrients in a proper time. To cope with such a problem, a fertilizer-control type coated fertilizer has been proposed and put into practical use, in which a nutrient supply pattern can be easily controlled as compared with conventional chemical fertilizers.

[0003] However, new problems have arisen in using coated fertilizers. That is, if the coated fertilizer is not a biodegradable resin, the coating may remain in the field and cause environmental pollution. In addition, the use of a solvent-type resin causes air pollution, affects workers (toxicity), fires (flammability), etc. in the production of coated fertilizers, and complicates removal and recovery of solvents. There is a problem that is very expensive. Therefore, there has been proposed a thermosetting resin which does not require the use of an organic solvent at the time of production and is easy to consider biodegradability.

[0004] Japanese Patent Publication No. 40-28927 discloses an example using a thermosetting resin as a coating material. This publication discloses fatty oil-modified alkyd resins, fatty oil-modified dicyclopentadiene polymers, diisocyanate-modified fatty oil polymers, and the like. However, since these resins have higher water permeability than olefin resins, it is difficult to control elution. A coating material using an oil-modified alkyd resin and wax has also been proposed. For example, JP-B-59-30679 discloses a granular fertilizer coated with a dry oil-modified phthalic acid resin varnish alone or a mixture thereof with an organic material (rosin, paraffin, wax, chlorinated paraffin, etc.). Is disclosed. Also, JP-A-6-56567,
JP-A-6-191980, JP-A-6-191981, JP-A-6-191981
No. 7-69770, JP-A-7-215789 discloses an oil-modified alkyd resin and an unsaturated oil having a conjugated double bond in the molecule as essential components, and a wax, a petroleum resin, rosin,
A coating material to which ester gum, boil oil and the like are added is disclosed.

Japanese Patent Application Laid-Open No. 8-151286 discloses that at least one material which is primarily coated with waxes and whose surface is selected from alkyd resins and water-soluble or swellable substances is used.
A multilayer coated granular fertilizer is disclosed in which a primary coating is melted or softened after being secondary coated with a material containing one kind. However, the alkyd-based coating material has a low coating film strength, so that it tends to cause defects, and the water-repellent effect of the wax does not work sufficiently, and it is difficult to control the elution with high precision.

On the other hand, there is US Pat. No. 3,264,089 using a polyurethane resin as a coating material. The present invention discloses a coated fertilizer using a urethane resin comprising a reaction product of a polyol compound and a polyisocyanate compound as a coating material. Japanese Patent Publication No. 54-39298 proposes a coated granular fertilizer in which a polyurethane coating layer is formed by reacting a polyoxypropylene compound with an isocyanate compound. Japanese Patent Publication No. 7-16648 discloses a solventless coating comprising a polyisocyanate, a phenol-formalin condensate, a hydroxy group-containing softening agent, and a catalytic amine, and JP-A-4-305085 discloses a polyisocyanate and a wool grease. Or a coating agent obtained by dissolving a polyol derived from lanolin or the like in an organic solvent, U.S. Pat.No. 5,374,292 discloses a coated slow-release fertilizer comprising MDI, polyethylene terephthalate, triethanolamine, and microcrystalline wax. ing.

Further, Japanese Patent Application Laid-Open No. 9-208355 discloses a coated fertilizer using two or more thermosetting resins (solvent-free liquid urethane resins) having different hydrophilicity (crosslinking density). JP-A 10-29886 discloses a coating agent comprising a polyurethane resin containing an oxyethylene group and an ester group, and JP-A-10-324587 discloses a coating agent derived from a polyol component and a polyisocyanate component. A coating agent comprising a polyurethane resin containing, is disclosed in JP-A-10-265288, isocyanate group-terminated prepolymer obtained from aromatic polyisocyanate, castor oil or castor oil derivative polyol, coated with a polyurethane resin comprising an amine polyol. A coated granular fertilizer is disclosed. However, among these polyurethane resins, there is a problem that the resin remains without being decomposed due to constituent components. Further, the polyurethane resin obtained by such a method has a limit, and the water permeability is higher than that of an olefin resin or the like. Japanese Patent Application Laid-Open No. 8-2988 discloses a method of treating with a wax before coating and drying and curing after coating with a thermosetting resin for the purpose of preventing the resin from adhering into the coating production tank. The elution cannot be adjusted with high accuracy.

With respect to the coating production method, for example, a method of heat-treating the obtained coated granular resin has been shown to be useful. Japanese Patent Application Laid-Open No. 7-315975 discloses a method of coating a granular substance as a method of coating a thermoplastic substance, first coating a thermoplastic substance, then secondary coating a thermosetting resin, and melting or softening the primary coated thermoplastic substance. However, the method disclosed here alone cannot sufficiently control the fertilizer elution. Also, the coating method is complicated. JP 8-
Japanese Patent No. 225387 discloses a method for producing a coated fertilizer, which comprises performing a heat treatment after coating a thermoplastic resin. Although this method is effective as a fertilizer elution control method, it is difficult to form a uniform film without a solvent because the thermoplastic resin has a high viscosity even when melted. further,
Japanese Patent Application Laid-Open No. 9-202683 discloses a method of forming a thermosetting resin coating film on a granular fertilizer surface by repeating spraying and drying, but the thermosetting resin alone increases coating film gap and elutes. Adjustment is difficult.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Using raw materials in consideration of degradability, in a simple manner, without extensive use of organic solvents, the results of repeated studies on a method of producing a coated granular fertilizer that is precisely adjusted without using an organic solvent, the present invention was completed. is there.

[0010]

That is, the present invention relates to a coated granular fertilizer coated with a coating material mainly composed of an oil-modified alkyd resin, a polyurethane resin comprising MDI and / or TDI, and carnauba wax. As described above, the advantage of using an oil-modified alkyd resin as the polyol component is that the dissolution can be adjusted by using the polyurethane resin alone, and the use of wax can improve the workability or control the dissolution. This is disclosed in JP-A-10-265288. However, in the present invention, the use of carnauba wax as the wax and the use of a reaction product of an oil-modified alkyd resin, which is a polyol component, and MDI and / or TDI as the polyurethane resin make it possible to easily increase the hardness industrially. In addition, it is possible to form a water-repellent coating with few defects.

More specifically, the first invention is a coating material comprising a polyurethane resin produced by the reaction of an oil-modified alkyd resin with MDI and / or TDI and carnauba wax as main components, A second aspect of the present invention relates to a coated granular fertilizer coated with a coating material having a weight ratio of polyurethane resin and carnauba wax in the range of 1: 0.25 to 1: 1. (B) and MDI and / or TDI (C) separately or a mixture of (A) and (B) and (C) separately sprayed and dried on fertilizer granules, characterized by being coated. And a method for producing the same. Further, the third invention relates to an oil-modified alkyd resin (A), carnauba wax (B) and MDI and / or TDI (C) separately or a mixture of (A) and (B) and (C). Is sprayed onto fertilizer granules separately and dried, and then heat-treated at a temperature equal to or higher than the softening or melting temperature of carnauba wax. The fourth invention relates to a method for producing coated granular fertilizer, which comprises spraying and drying. Is repeatedly performed at least five times or more.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The oil-modified alkyd resin used in the present invention is obtained by a known method, for example, a polybasic acid such as phthalic anhydride and maleic anhydride and a polyhydric alcohol such as glycerin and pentaerythritol, and The denaturing agent is a general one obtained by heating and condensing natural vegetable oil, animal oil, or the like, and is not particularly limited. In the present invention, in order to use this as a coating material by urethane,
The hydroxyl value is preferably from 20 to 400 from the viewpoint of the strength of the coating film. As for the acid value, when the acid value is high, the urethane reaction is inhibited, the drying property of the film is deteriorated, and the desired film strength cannot be obtained.
More preferably, it is 10 or less. It is desirable that the viscosity of the oil-modified alkyd resin used is low, and from the viewpoint of film strength when the resin is urethanized, linseed oil and castor oil are used as modifiers, and phthalic anhydride is used as the polybasic acid. Glycerin is particularly recommended as the polyhydric alcohol. However, it is not limited to these.

The isocyanate compounds used for urethanization are MDI and TDI. See MDI
Is purified monomeric MDI (4,4'-
Diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate), and polymeric MDI containing oligomers. TDI is 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. Also, mixtures thereof can be used. However, among these, polymeric MDI is most preferable from the viewpoint of film formation.

Oil-modified alkyd resin and MDI and / or T
The ratio of DI is preferably from 1.1 to 3.0 as a molar ratio (NCO / OH) between the isocyanate group and the hydroxyl group of the polyol component. If the ratio is out of the above range, crosslinking of the coating film is reduced and sufficient water resistance cannot be obtained, or the coating strength is reduced to easily cause defects in the coating film, and it is extremely difficult to control the elution of fertilizer.

It is a useful technique to add a catalyst for crosslinking the oil-modified alkyd resin and for accelerating the reaction during urethanization. Known and commonly used ones can be used,
As the former crosslinking catalyst, for example, manganese naphthenate,
Organic salts such as cobalt octanoate can be used. As the latter catalyst, for example, organic salts such as potassium octanoate and amine compounds such as triethylenediamine can be used.

The quality of carnauba wax is not particularly limited, and any commercially available carnauba wax can be used. A purified product or a product processed as an emulsion can also be used.

As for the amount of carnauba wax, the mass ratio of polyurethane resin to carnauba wax is 1: 0.25 to
Used in the range of 1: 1. When the amount of carnauba wax is small, the effect of water repellency cannot be obtained, and it is difficult to adjust the elution of fertilizer. If the amount is large, the strength of the coating is reduced, and the coating is liable to be defective, so that it is impossible to sufficiently control the fertilizing effect.

The fertilizer that can be coated is not particularly limited as long as it is granular. For example, monofertilizers such as urea, ammonium sulfate, ammonium nitrate, salt ammonium chloride, potassium fertilizer, and compound fertilizers such as phosphorous ammonium, phosphorus ammonium sulfide, and phosphorous ammonium nitrate potassium Is a representative. The particle size of the fertilizer particles is not particularly limited, but those having a size of 1 mm to 5 mm are preferably used.

Next, the method for producing the coated granular fertilizer of the present invention will be described in more detail. The method for producing the coated granular fertilizer is divided into a step of forming a film on the surface of the fertilizer particles and a step of heating the obtained coated particles. Can be

The method of coating the granular fertilizer is a method in which each coating material is adhered to the granular fertilizer in a flowing or rolling state, and heated by hot air or the like to harden on the granular fertilizer to form a coating. Can be used. A known method can be used for flowing and rolling the granular fertilizer. For example, a fluidizing device or a jet fluidizing device can be used for fluidization, and a rotating pan or rotating drum device can be used for rolling.

Each of the coating materials is liquefied and adjusted to have a viscosity of 300 cp or less. For example, the oil-modified alkyd resin is heated to 80 to 120C. MDI and / or TDI are those which are 300 cp or less at room temperature as they are, and those which are solid are heated to a melting point or higher to be liquefied.
Carnauba wax is used alone or dispersed in an oil-modified alkyd resin. 90-1 in each case
Use what is liquefied by heating to 20 ° C. If the viscosity of the coating material exceeds 300 cp, the workability deteriorates, a uniform film is not formed, and it becomes difficult to control the elution of fertilizer, which is not preferable.

As a mode of use of the coating material in the present invention, an oil-modified alkyd resin and MDI and / or TDI and carnauba wax can be mixed and used, but if the storage time is long, polyurethane resin is partially formed. And not desirable. The best method is a method in which an oil-modified alkyd resin and carnauba wax are mixed and used separately from MDI and / or TDI. Of course, the three can be used separately.

The method of adhering the coating material to the fertilizer particles is not particularly limited as long as it can be uniformly applied to the fertilizer particles, and can be carried out without being limited to spraying or dripping. Further, each coating material may be sprayed from the same location or from different locations. Heating is performed to cure the coating. However, if the temperature is too low, the viscosity of the sprayed solution increases, and a uniform film is not formed on the particle surface. On the other hand, if the temperature is too high, the carnauba wax does not cure and a film is not formed, so that the heating temperature is preferably from 50C to 75C. It is also possible to use organic solvents to lower the viscosity of the spray solution, to form a uniform coating on the surface of the fertilizer granules and to increase the reactivity.

The heating temperature in the heat treatment step is generally from 80 ° C. to 110 ° C. When the temperature is lower than 80 ° C., the carnauba wax does not soften and melt, so that fine gaps in the polyurethane resin are not filled or a carnauba wax layer is not formed on the particle surface. Further, the reaction of the resin is not promoted, and a water-repellent film is not formed. 11
If the temperature is higher than 0 ° C., it adheres to the heating device or carnauba wax melts to form a fertilizer lump, so that a uniform coating cannot be obtained, and it is extremely difficult to adjust the coating elution. The heating time depends on the heating temperature, but is from 5 minutes to 2 hours, preferably 1 hour.
5 minutes to 1 hour. If the length is too short, the carnauba wax will not move sufficiently in the polyurethane resin, and if it is too long, the carnauba wax will flow from the particle surface and a sufficient elution control effect will not be obtained.
A general dryer can be used as the heating device. Also,
Heat treatment can be performed in the coating device, but if the stirring is performed for the purpose of increasing thermal efficiency, the coating may be defective.
In the case of performing the heat treatment in a static state or stirring, it is preferable to reduce the stirring speed.

As long as the properties of the coating of the present invention are not impaired, it is also possible to add an organic or inorganic additive to the coating composition as an auxiliary means for improving the film forming properties and controlling the fertilizing effect. . For example, alkyd resin, urethane resin, aliphatic ester, rosin and derivatives thereof, surfactant, talc, calcium carbonate and the like can be mentioned.

Next, regarding the control of the elution of the fertilizer component, the elution is controlled by the number of times of spray-drying. It is preferable to repeat the spray-drying of the coating material at least five times or more. In the case of less than 5 times, the fertilizer component elutes quickly and the effect of the coated granular fertilizer cannot be expected. Generally, it is about 7 to 50 times. Although it depends on the composition of the coating material, the ratio of the granular fertilizer and the coating material, and the uniformity of the coating film, if it exceeds 50 times, the elution will be lost slowly, and the fertilizing time will be lost. It depends on the type of fertilizer, crops applied, etc., but the coverage,
The ratio of the coating material to the coated granular fertilizer is 7 to 20% by mass. Spray-the more fertilizer components elute as the number of drying increases,
The elution time is delayed.

[0027] The coated granular fertilizer thus obtained is one in which the dissolution is precisely controlled. It is presumed that the molecular structure of carnauba wax greatly contributes to obtaining an excellent synergistic effect as in the present invention among the three members of the oil-modified alkyd resin, MDI and / or TDI, and carnauba wax. That is, carnauba wax is obtained from carnauba palm and contains a higher fatty acid ester as a main component. The constituent components include molecules having an unsaturated bond or a hydroxy group, and at the time of film formation, cross-linking with higher fatty acid esters or alkyd resin or reacting with MDI and / or TDI to form a complex structure, and further increase hardness. Is presumed to form a film having a high density Further, as an effect of the heat treatment, an excellent water-resistant structure is formed by uniform movement of the wax component in the coating. In addition, it is considered that the moderate reactivity of the carnauba wax with the resin and the appropriate penetration into the resin described above result in low initial elution, and then release the fertilizer component with high accuracy.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited thereto. Unless otherwise specified, all percentages indicate mass%.

(Example 1) Granular urea (average particle size 3 mm) 5
00 g was charged into a centrifugal rolling granulation coating apparatus (rotating disk diameter 230 mm) equipped with a hot air generator, and 360 rpm.
, And the granular fertilizer was brought into a rolling state, and hot air was sent from the lower part and kept at 70 ° C. Cobalt aliphatic monocarboxylate solution (Co concentration 8%) as a catalyst on 40 g of linseed oil castor oil-modified alkyd resin (hydroxyl value 190) having an oil length of 47%
0.2 g of a potassium aliphatic monocarboxylate solution (concentration 7
(0%) was added and heated to 100 ° C. to prepare a polyol solution (Solution A). In addition, carnauba wax (P
30 g of VP S / A (manufactured by BRAZIL) at 100 ° C.
To obtain a melt (solution B). Liquid A and polymeric MD are added to heated and tumbled granular urea.
I (manufactured by Sumitomo Bayer Urethane, trade name Sumijur 44)
V10) was sprayed from two locations using a two-fluid nozzle at a rate of 0.11 g / sec for Liquid A and at a rate of 0.08 g / sec for polymeric MDI for 10 seconds. Per second for 10 seconds, tumbled for 5 minutes and dried to form a film. This spray-drying step was repeated 20 times to produce a coated granular fertilizer (Example 1-1). Next, the coated granular fertilizer is taken in a stainless steel vat and placed in a ventilation dryer maintained at 90 ° C. for 1 hour.
It was left for a while to perform a heat treatment (Example 1-2). Table 1 shows the coverage and elution rate of the coated granular fertilizer and the coated granular fertilizer subjected to the heat treatment.

Example 2 40 g of linseed oil castor oil-modified alkyd resin (having a hydroxyl value of 190) having an oil length of 47% and carnauba wax (manufactured by PVP S / A (BRAZIL)) 30
g, a cobalt salt of an aliphatic monocarboxylate (C
0.2 g of an o-concentration (8%) and 0.4 g of a potassium aliphatic monocarboxylate solution (concentration of 70%) were heated to 100 ° C. to prepare a melt (liquid C). Using the same apparatus as in Example 1, the liquid C and polymeric MDI (Sumitomo Bayer Urethane, trade name Sumidur 44V10) were separately added to the heated and tumbled granular urea in the same manner as in Example 1 from two places. The liquid C was sprayed at a rate of 0.19 g / sec and the polymeric MDI was sprayed at a rate of 0.08 g / sec for 10 seconds by a two-fluid nozzle, tumbled for 5 minutes and dried to form a film. This spray-drying process was repeated 20 times to produce a coated granular fertilizer. (Example 2-1) Next, the coated granular fertilizer was taken in a stainless steel vat, placed in a ventilation drier maintained at 90 ° C., left for 1 hour, and subjected to heat treatment. (Example 2-2)
Table 1 shows the coverage and elution rate of the coated granular fertilizer and the coated granular fertilizer subjected to the heat treatment.

(Example 3) A coated granular fertilizer was produced under the same coating conditions and heat treatment conditions as in Example 2-2 except that the spray-drying step was performed 25 times. Table 1 shows the coverage and elution rate of the coated granular fertilizer.

(Comparative Example 1) No carnauba wax was used, the spraying rate was 0.15 g / sec for Liquid C, and Polymeric M was used.
Example 2 except that DI was changed to a speed of 0.11 g / sec.
The coated granular fertilizer was produced in the same manner and under the same conditions as in Example-1.
Table 1 shows the coverage and elution rate of the coated granular fertilizer.

(Comparative Example 2) Example 2-2, except that paraffin wax (trade name: 155, manufactured by Nippon Seiro) was used instead of carnauba wax, and the temperature of the granular urea in the rolling state was changed to 60 ° C. A coated granular fertilizer was produced in the same manner and under the same conditions. When coating was carried out with this composition, a uniform coating was not formed and spots were formed. Table 1 shows the coverage and elution rate of the coated granular fertilizer.

Comparative Example 3 In place of carnauba wax, an alcohol type wax (product name: OX-194, manufactured by Nippon Seiro) was used.
Except for using 9), a coated granular fertilizer was produced in the same manner and under the same conditions as in Example 2-2. Table 1 shows the coverage and elution rate of the coated granular fertilizer.

[0035]

[Table 1]

Coverage: coverage (%) = (weight of coating film / weight of coated granular fertilizer) × 100 Elution rate: 2.5 g of coated granular fertilizer is added to 50 ml of water, the container is closed, and the temperature is kept at 25 ° C. Put in the tank. This was taken out after a certain period, and the fertilizer and the solution were separated ^(*) , the nitrogen component eluted in the solution was quantified, and the elution rate was calculated by the following equation. Dissolution rate (%) = (Nitrogen content in solution / Nitrogen content in coated granular fertilizer) x 100 ^(**) * For each measurement of nitrogen component, 5 new fertilizers were separated each time.
0 ml of water was added. ** The elution rate in the table indicates a cumulative value.

From Table 1, it can be seen that the initial elution is low by the combined use of carnauba wax, and that the initial elution is further suppressed by heat treatment.

[0038]

The coated granular fertilizer of the present invention can precisely control the elution of fertilizer components over a long period of time. Since the coating material is decomposed, it does not remain in the soil, and there is no need to use organic solvents, so there is no danger of fire, etc.
It does not require solvent recovery and can be easily manufactured with simple equipment.

Claims (4)

[Claims] 1. A coating material comprising a polyurethane resin produced by the reaction of an oil-modified alkyd resin with diphenylmethane diisocyanate (MDI) and / or tolylene diisocyanate (TDI) and carnauba wax as main components. A coated granular fertilizer coated with a coating material having a weight ratio of resin to carnauba wax in the range of 1: 0.25 to 1: 1. 2. An oil-modified alkyd resin (A), carnauba wax (B) and MDI and / or TDI (C) separately or a mixture of (A) and (B) and (C) separately. A method for producing coated granular fertilizer which is sprayed and dried on fertilizer granules. 3. An oil-modified alkyd resin (A), carnauba wax (B) and MDI and / or TDI (C) separately or a mixture of (A) and (B) and (C) separately. A method for producing a coated granular fertilizer, comprising spraying and drying fertilizer granules, followed by heat treatment at a temperature higher than the softening or melting temperature of carnauba wax. 4. The method for producing a coated granular fertilizer according to claim 2, wherein spraying and drying are repeated at least 5 times or more.