Coated granular fertilizer

Abstract

We have found a problem with coated granular fertilizers that have a coating containing hydrogenated plant oil, where the leaching of fertilizer components may occur prematurely after storage. The present invention aims to provide a coated granular fertilizer that is biodegradable and in which the premature leaching of fertilizer components after storage is suppressed. [Solution] A coated granular fertilizer comprising granular urea and a coating film covering the granular urea, wherein the coating film contains a hardened plant oil, the melting point of the hardened plant oil is 60°C or higher and 100°C or lower, and the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.0 Å) of the coating film in X-ray diffraction measurement is 1.2 or higher.

Description

Technical Field

[0001] The present invention relates to coated granular fertilizers.

Background Art

[0002] Coated granular fertilizers have advantages such as controlling the elution of fertilizer components and being able to maintain their efficacy once applied, thereby reducing the number of applications.

[0003] For example, Patent Document 1 describes a coated granular fertilizer including a resin coating layer provided on the surface of granular urea and a protective layer containing a vegetable hardened oil provided outside the resin coating layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present inventors have found a problem that in a coated granular fertilizer having a coating containing a vegetable hardened oil, the elution of fertilizer components may be accelerated after storage. An object of the present invention is to provide a coated granular fertilizer having decomposability and suppressing the acceleration of elution of fertilizer components after storage.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be solved by setting the peak intensity ratio in the X-ray diffraction measurement of the coating of a coated granular fertilizer containing a vegetable hardened oil, more specifically, the peak intensity at 17 Å / the peak intensity at 4.0 Å or the peak intensity at 17 Å / the peak intensity at 4.5 Å within a specific range.

[0007] In other words, the coated granular fertilizer according to the present invention may have, but is not limited to, the following configurations. [1] The device comprises granular urea and a coating that covers the granular urea. The aforementioned coating contains a hydrogenated vegetable oil, The melting point of the aforementioned hydrogenated vegetable oil is 60°C or higher and 100°C or lower. A coated granular fertilizer in which the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.0 Å) of the coating in X-ray diffraction measurements is 1.2 or greater. [2] The device comprises granular urea and a coating that covers the granular urea. The aforementioned coating contains a hydrogenated vegetable oil, The melting point of the aforementioned hydrogenated vegetable oil is 60°C or higher and 100°C or lower. A coated granular fertilizer in which the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.5 Å) of the coating measured by X-ray diffraction is 1.5 or greater. [3] The coated granular fertilizer according to [1] or [2], wherein the aforementioned hydrogenated plant oil is at least one selected from the group consisting of hydrogenated castor oil, hydrogenated rapeseed oil, and hydrogenated soybean oil. [4] The coated granular fertilizer according to [1] or [2], wherein the aforementioned hardened plant oil is hardened castor oil. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a coated granular fertilizer that is biodegradable and in which the premature leaching of fertilizer components after storage is suppressed. [Modes for carrying out the invention]

[0009] The coated granular fertilizer according to the present invention will be described below.

[0010] The coated granular fertilizer comprises granular urea and a coating film that covers the granular urea.

[0011] The coated granular fertilizer contains granular urea.

[0012] The granular urea is a granular material containing a urea component. The granular urea may be a granular material in which the urea component is granulated alone, or it may be a granular material containing the urea component and any additives. Examples of such optional additives include anti-flotation agents, composition uniformity promoters, effect-enhancing agents, colorants, and granulation promoters.

[0013] The particle size of the granular urea is not particularly limited, but is usually 0.1 to 15.0 mm.

[0014] The granular urea can be produced by known methods. The granular urea can be produced by granulating the urea component alone, or by mixing the urea component with the optional additive and then granulating the mixture.

[0015] The coating contains hydrogenated vegetable oil.

[0016] The aforementioned hydrogenated vegetable oil can be obtained by adding hydrogen to a naturally derived or synthetic vegetable oil containing unsaturated fatty acid triglycerides to saturate the unsaturated bonds of the unsaturated fatty acid triglycerides. The aforementioned hydrogenated vegetable oil can also be obtained by chemical synthesis. Examples of the aforementioned hydrogenated vegetable oil include hydrogenated castor oil, hydrogenated rapeseed oil, hydrogenated soybean oil, hydrogenated palm oil, hydrogenated peanut oil, hydrogenated jojoba oil, hydrogenated cottonseed oil, and hydrogenated coconut oil.

[0017] The aforementioned hardened plant oil has moderate decomposition properties in fertilization environments such as soil. Specifically, since the hardened plant oil does not decompose immediately in the fertilization environment, it allows the coating to exhibit leaching control properties. Furthermore, the hardened plant oil decomposes at a moderate rate such that its presence in the fertilization environment does not pose a problem. In other words, a coated granular fertilizer equipped with a coating containing the hardened plant oil exhibits excellent decomposition and leaching control properties. The decomposition properties of the hardened plant oil can be measured according to the procedure described in the Examples section below.

[0018] The vegetable hardened oil is solid at 25°C. The melting point of the vegetable hardened oil is 60°C or higher and 100°C or lower, and may be 80°C or higher and 90°C or lower. Since the vegetable hardened oil with such a melting point can be melted by heating, it can be handled in a liquid state without using a solvent. Furthermore, when using the vegetable hardened oil with such a melting point, it is possible to prevent sticking between the coated granular fertilizers or between the coated granular fertilizer and the rotary drum during the production of the coated granular fertilizer, and the productivity of the coated granular fertilizer is improved. The productivity of the coated granular fertilizer can be measured according to the procedure described in the column of the examples below. The freezing point of the vegetable hardened oil is 60°C or higher and 100°C or lower, and may be 80°C or higher and 90°C or lower. Note that although the melting point and the freezing point generally have the same value, in the case of the vegetable hardened oil, the melting point may be higher than the freezing point.

[0019] The vegetable hardened oil has low adhesiveness. By including a vegetable hardened oil with low adhesiveness in the coating of the coated granular fertilizer, caking between the coated granular fertilizers during production and storage can be suppressed, and the sticking property of the coated granular fertilizer is improved. The sticking property of the coated granular fertilizer during storage can be measured according to the procedure described in the column of the examples below.

[0020] Since the vegetable hardened oil has lower water vapor permeability compared to biodegradable resins, it is excellent from the viewpoint of improving the elution control property of fertilizer components. Since the vegetable hardened oil has higher fluidity when melted by heating compared to the biodegradable resin, it is less likely to cause caking during the production of the coated granular fertilizer, and the productivity of the coated granular fertilizer is improved.

[0021] The content of the vegetable hardened oil in the coating may be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0022] The coating may contain only one of the hydrogenated vegetable oils, or it may contain two or more. The coating may contain at least one selected from the group consisting of hydrogenated castor oil, hydrogenated rapeseed oil, and hydrogenated soybean oil.

[0023] The coated granular fertilizer preferably does not contain biodegradable resins. Examples of biodegradable resins include polylactic acid, polyhydroxyalkanoate, polybutylene adipate terephthalate, polycaprolactone, polybutylene succinate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, polyaspartic acid, cellulose fatty acid ester, and polybutylene succinate adipate.

[0024] Preferably, the coating does not contain a resin that is not biodegradable. Examples of resins that are not biodegradable include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include olefin resins, diene resins, and polyvinyl chloride. Examples of olefin resins include polyethylene, polypropylene, polybutene, polystyrene, ethylene-propylene copolymer, butene-ethylene copolymer, butene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, and ethylene-carbon monoxide copolymer. Examples of diene resins include butadiene copolymer, isoprene polymer, chloroprene polymer, butadiene-styrene copolymer, and styrene-isoprene copolymer. Examples of thermosetting resins include epoxy resin, alkyd resin, phenol resin, urea resin, melamine resin, and silicone resin.

[0025] The coating may contain any additives. Examples of such additives include antibacterial agents. The content of the additives in the coating is, for example, 0.1 to 10% by mass.

[0026] The mass ratio of the granular fertilizer to the coating may be 1:0.1 or more and 1:0.5 or less.

[0027] The thickness of the coating is typically 30 to 500 μm. The thickness of the coating can be measured by observing a cross-section passing through the center of the coated granular fertilizer using a scanning electron microscope (Hitachi High-Tech Corporation, SU-3800) in BSE mode. Alternatively, it can be determined by drawing 10 line segments perpendicular to the coating for each piece of coated granular fertilizer and averaging their lengths.

[0028] The method for producing the coated granular fertilizer comprises a first step of tumbling the granular urea, a second step of adding the hardened vegetable oil to the tumbling granular urea, and a third step of cooling the obtained coated granular fertilizer.

[0029] In the first step, the granular urea in the rolling state may be heated. The heating temperature of the granular urea may be 50°C to 120°C, or 70°C to 100°C.

[0030] In the second step, the hydrogenated vegetable oil may be heated and melted. The heating and melting temperature is higher than the melting point of the hydrogenated vegetable oil and may be 70°C, 80°C, 90°C, or 105°C.

[0031] In the third step, the coated granular fertilizer may be in a rolling state or may be left standing. The cooling rate of the coated granular fertilizer in the third step (hereinafter referred to as the cooling rate) may be 0.1 to 8.0°C / min, 0.1 to 5.0°C / min, or 0.3 to 3.0°C / min. The third step may be carried out by allowing the coated granular fertilizer to cool at room temperature, by blowing gas onto the coated granular fertilizer, or by cooling the coated granular fertilizer using a water bath, ice bath, ice bath, or oil bath set to any temperature.

[0032] In the first step, the heating temperature of the granular urea may be lower than or higher than the melting point or freezing point of the hydrogenated vegetable oil. Preferably, the heating temperature of the granular urea is lower than the melting point or freezing point of the hydrogenated vegetable oil. The difference between the melting point or freezing point of the hydrogenated vegetable oil and the heating temperature of the granular urea may be 25°C or less, 20°C or less, or 10°C or less. It is believed that by having the difference between the melting point or freezing point of the hydrogenated vegetable oil and the heating temperature of the granular urea within this range, it is possible to prevent the hydrogenated vegetable oil from being excessively cooled by the granular urea in the second step. The difference between the heating temperature of the granular urea in the first step and the heating and melting temperature in the second step may be 50°C or less, 35°C or less, or 25°C or less. It is believed that by having the difference between the heating temperature of the granular urea and the heating and melting temperature within this range, it is possible to prevent the hydrogenated vegetable oil from being excessively cooled by the granular urea in the second step.

[0033] The method for producing the coated granular fertilizer may include a step of adding a lubricant such as liquid paraffin or other optional components between the first and second steps. The step of adding other optional components may be carried out under heating conditions. The method for producing the coated granular fertilizer may also include a step of adding an optional additive such as a surfactant or an anti-caking agent to the surface of the obtained coated granular fertilizer after the third step.

[0034] The crystalline structure of the coating of the aforementioned coated granular fertilizer can be analyzed by X-ray diffraction measurement. The diffraction conditions for the X-ray diffraction measurement are given by Bragg's equation (2dsinθ=nλ(n=1,2,3...)), where d is the lattice constant, θ is the angle of incidence, λ is the wavelength of the X-ray, and n is a natural number. In the X-ray diffraction measurement, a diffraction peak is observed at the angle of incidence θ that satisfies Bragg's equation. The XRD peak intensity ratio of the coating of the aforementioned coated granular fertilizer can be measured according to the procedure described in the Examples section below.

[0035] The coating of the aforementioned coated granular fertilizer shows peaks at at least d=4.0(±0.2)Å, 4.5(±0.2)Å, 6.3(±0.2)Å, and 17(±0.2)Å in X-ray diffraction measurements. The value obtained by dividing the peak intensity of the coating film of the coated granular fertilizer at d=17(±0.2)Å by the peak intensity at d=4.0(±0.2)Å (hereinafter sometimes referred to as the peak intensity at 17Å / peak intensity at 4.0Å) may be 1.0 or greater, 1.2 or greater, 1.2 to 10, 1.2 to 5.0, 1.2 to 4.0, or 1.2 to 3.0. The value obtained by dividing the peak intensity of the coating film of the coated granular fertilizer at d=17(±0.2)Å by the peak intensity at d=4.5(±0.2)Å (hereinafter sometimes referred to as the peak intensity at 17Å / peak intensity at 4.5Å) may be 1.0 or greater, 1.5 or greater, 1.5 to 10, 1.5 to 5.0, 1.5 to 7.0, or 1.5 to 4.0.

[0036] The coated granular fertilizer can be used for cultivating crops in paddy fields, such as grasses. The coated granular fertilizer may be applied to paddy fields alone or as part of a compound fertilizer with other fertilizers.

[0037] In this specification, the elution rate E1 of the fertilizer components when the coated granular fertilizer is left standing in water at a concentration of 2.5 g / 100 mL (25°C, 2 weeks) is referred to as the elution rate. The elution rate can be measured according to the procedure described in the Examples section below. The elution controllability of the coated granular fertilizer can be evaluated based on the value of E1. In this specification, the elution rate E2 of the fertilizer components after the coated granular fertilizer is left standing in a constant temperature chamber set to 54°C for two weeks, and then left standing in water at a concentration of 2.5 g / 100 mL (25°C, two weeks), is referred to as the elution rate after storage. Leaving the fertilizer standing at 54°C for two weeks is equivalent to leaving it standing at room temperature for approximately two years. The elution rate after storage can be measured according to the procedure described in the Examples section below. The storage stability of the coated granular fertilizer can be evaluated based on the E2-E1 value.

[0038] The coated granular fertilizer can be spread onto the soil using a spreader such as a side-dressing fertilizer applicator. [Examples]

[0039] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples.

[0040] [Granular urea] Granular urea (manufactured by China BlueChemical Limited, particle size: approx. 3mm) [Vegetable hydrogenated oil] Castor Oil Hydrogenated Oil, manufactured by Ito Oil Co., Ltd., melting point 80-90°C (hereinafter referred to as Castor Oil Hydrogenated Oil 1). Yokozeki Oil & Fat Industry Co., Ltd.'s "Highly Hydrogenated Rapeseed Oil," melting point 67°C (hereinafter referred to as "highly hydrogenated rapeseed oil"). [Petroleum-based wax] "HNP-51" manufactured by Nippon Seiro Co., Ltd. (hereinafter referred to as paraffin wax). "Sazol C80" manufactured by Kato Yoko Co., Ltd. (hereinafter referred to as FT Wax) [Plant-based wax] "Refined Carnauba Wax No. 2" manufactured by Kato Yoko Co., Ltd. (hereinafter referred to as "carnauba wax") "Refined Candelilla Wax" manufactured by Kato Yoko Co., Ltd. (hereinafter referred to as "candelilla wax") [others] Lunac S-98 (hereinafter referred to as stearic acid), manufactured by Kao Chemical Co., Ltd. Nissan Electrol WEP-5 (hereinafter referred to as fatty acid ester), manufactured by NOF Corporation. "Calcol 220-80" (hereinafter referred to as behenyl alcohol), manufactured by Kao Chemical Co., Ltd.

[0041] [Example 1] Granular urea 1 (1000 parts by mass) was placed in a rotating tank and turned. The granular urea was then heated to approximately 70°C with hot air, after which liquid paraffin (MORESCO White P-350P, manufactured by MORESCO Corporation) (10 parts by mass) was added, and the tank was turned for 5 minutes. Paraffin-coated granular urea was kept in a rolling state, and castor hydrogenated oil 1 (210 parts by mass) heated and melted at 105°C was added. The rolling state was maintained under heating conditions for 3 minutes or more. Subsequently, the mixture was cooled to near room temperature at a cooling rate of 0.4°C / min to obtain coated granular fertilizer (hereinafter referred to as coated granular fertilizer 1).

[0042] [Example 2] Coated granular fertilizer was obtained in the same manner as in Example 1, except that the cooling rate was set to 1.6°C / min (hereinafter referred to as Coated Granular Fertilizer 2).

[0043] [Example 3] A coated granular fertilizer was obtained in the same manner as in Example 1, except that the cooling rate was set to 2.8°C / min (hereinafter referred to as this coated granular fertilizer 3).

[0044] [Comparative Example 1] A coated granular fertilizer was obtained in the same manner as in Example 1, except that the cooling rate was set to 9.0°C / min (hereinafter referred to as Comparative Coated Granular Fertilizer 1).

[0045] [Comparative Examples 2-3] Coated granular fertilizer was obtained in the same manner as in Example 2, except that paraffin wax or stearic acid was used instead of castor oil 1, and the heating temperature of the granular urea was set to 55°C (hereinafter, these will be referred to as comparative coated granular fertilizer 2 or 3, respectively).

[0046] [Comparative Examples 4-5] Coated granular fertilizer was obtained in the same manner as in Example 2, except that FT wax or carnauba wax was used instead of castor oil 1, and the heating temperature of the granular urea was set to 55°C (hereinafter referred to as comparative coated granular fertilizer 4 or 5, respectively).

[0047] [Evaluation of the decomposition properties of hydrogenated plant oils, petroleum-based waxes, etc.] (Method for preparing evaluation samples) Ten g each of the samples shown in Table 1, such as hydrogenated vegetable oil and petroleum-based wax, was placed in a constant temperature incubator set to 105°C and melted. The molten samples were cast onto a glass plate using a film applicator (Allgood Co., Ltd., 600 μm gap), cooled and solidified at room temperature, and a film with a thickness of approximately 300 μm was created. (Evaluation method) 20g of soil (collection site: Kasai City, Hyogo Prefecture) was placed in a 50mL plastic cup. A test specimen was prepared by cutting a 2cm square, approximately 100mg in size from the prepared film and weighing it (M1). The test specimen was placed on top of the soil, and 20g of soil was added on top. The specimen was then lightly tapped on the ground about 10 times to pack it. This plastic cup and a water-filled cup for moisture retention were placed on a tray, put into a plastic bag, and the opening was lightly tied. The tray was placed in a constant temperature incubator set to 28°C, and the weight of the cup was measured every half month from the start of the test. If a change was observed, water was added using a spray bottle. After one month, the test specimen was collected, lightly washed, and thoroughly dried at room temperature for at least one night. The mass of the test specimen was measured (M2), and the mass loss rate (W = M2 / M1 × 100 (%)) was calculated. (Evaluation Criteria) A: Mass reduction rate W is 20% or more but less than 40% B: Mass loss rate W is 10% or more but less than 20%, or 40% or more but less than 60% C: Mass loss rate W is less than 10% or 60% or more. A rating of A indicates that the coated granular fertilizer has good decomposition properties as a coating. The results are shown in Table 1.

[0048] [Table 1]

[0049] [Evaluation of the manufacturability of coated granular fertilizers] (Evaluation method) The degree of adhesion between coated granular fertilizers or between coated granular fertilizers and the rotating tank during the production of coated granular fertilizers 1-3 and comparative coated granular fertilizers 1-5 was visually evaluated. The results are shown in Tables 2 and 4. (Evaluation Criteria) ○: Almost no adhesion occurred between the coated granular fertilizers themselves or between the coated granular fertilizers and the rotating tank. ×: Significant adhesion occurred between the coated granular fertilizers themselves or between the coated granular fertilizers and the rotating tank.

[0050] [Table 2]

[0051] [Evaluation of the adhesive properties of coated granular fertilizers during storage] (Evaluation method) 50g of the coated granular fertilizer 1 was placed in a cylindrical container, and a 5kg weight was placed on top of it. The container was then left undisturbed in a constant temperature chamber set to 40°C for 24 hours. After that, the coated granular fertilizer 1 was removed from the container, and the degree of adhesion between the granular fertilizer particles was visually evaluated. The results are shown in Table 3. (Evaluation Criteria) ○: Almost no adhesion occurred between the coated granular fertilizers. ×: Significant adhesion occurred between the coated granular fertilizers.

[0052] [Table 3]

[0053] [Elution rate] 2.5 g of coated granular fertilizer 1 (60-80 granules) was placed in a sample bottle, 100 mL of water was added, and the mixture was left to stand at 25°C. After 14 days, 0.6 mL of water was taken from the sample bottle, and the urea concentration was measured using a UV-Vis spectrophotometer (UV-1900i, Shimadzu Corporation). Based on the measured urea concentration, the urea elution rate E1 (%) from coated granular fertilizer 1 was calculated. The elution rates were similarly evaluated for coated granular fertilizers 2-3 and comparative coated granular fertilizer 1. The results are shown in Table 4. (Evaluation Criteria) A: Dissolution rate E1 is less than 20% B: Dissolution rate E1 is 20% or more but less than 35% C: Dissolution rate E1 is 35% or higher Dissolution control can be evaluated as good if the evaluation is A or B.

[0054] [Storage stability] 2.5 g of coated granular fertilizer 1 (60-80 granules) was placed in a sample bottle and left to stand in a constant temperature incubator set to 54°C for two weeks. Then, 100 mL of water was added and left to stand at 25°C. After 14 days, 0.6 mL of water was taken from the sample bottle, and the urea concentration was measured using a UV-Vis spectrophotometer (UV-1900i, Shimadzu Corporation). Based on the measured urea concentration, the elution rate E2 (%) of coated granular fertilizer 1 after storage was calculated. The elution rates after storage were similarly evaluated for coated granular fertilizers 2-3 and comparative coated granular fertilizer 1. The results are shown in Table 4. (Evaluation Criteria) A: E2-E1 is less than 5% B: E2-E1 is between 5% and less than 10% C:E2-E1 is 10% or more If the evaluation is A or B, it can be considered to have good storage stability.

[0055] [Evaluation of XRD peak intensity ratio of coated granular fertilizer film] The coating of coated granular fertilizer 1 (approximately 100g) was scored with a utility knife and immersed in water overnight to dissolve the fertilizer components. Afterward, it was thoroughly air-dried at room temperature, and the resulting coating was ground in a mortar to obtain a powdered coating sample. Using an XRD (desktop XRD device D2 Phaser, BRUKER), CuKα (λ=1.542Å) was used as the radiation source, with an output of 0.3kW, a scanning angle 2θ=2.0~30.0°, and a measurement speed of 2° / min to obtain the diffraction pattern of the powdered coating sample. The peak intensity ratios (17Å peak intensity / 4.0Å peak intensity) and peak intensity ratios (17Å peak intensity / 4.0Å peak intensity) for coated granular fertilizers 1-3 and comparative coated granular fertilizer 1 are shown in Table 4. In this specification, peak intensity refers to the height of the peak in X-ray diffraction measurement (Count per second).

[0056] [Table 4]

Claims

1. The device comprises granular urea and a coating that covers the granular urea. The aforementioned coating contains a hydrogenated vegetable oil, The melting point of the aforementioned hydrogenated vegetable oil is 60°C or higher and 100°C or lower. A coated granular fertilizer in which the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.0 Å) of the coating in X-ray diffraction measurements is 1.2 or greater.

2. The device comprises granular urea and a coating that covers the granular urea. The aforementioned coating contains a hydrogenated vegetable oil, The melting point of the aforementioned hydrogenated vegetable oil is 60°C or higher and 100°C or lower. A coated granular fertilizer in which the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.5 Å) of the coating in X-ray diffraction measurement is 1.5 or greater.

3. The coated granular fertilizer according to claim 1 or 2, wherein the aforementioned hydrogenated plant oil is at least one selected from the group consisting of hydrogenated castor oil, hydrogenated rapeseed oil, and hydrogenated soybean oil.

4. The coated granular fertilizer according to claim 1 or 2, wherein the aforementioned hardened plant oil is hardened castor oil.

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