Coated granular fertilizer

Abstract

A coated granular fertilizer comprising granular urea and a coating film that covers the granular urea, wherein the coating film contains a hydrogenated vegetable oil, the melting point of the hydrogenated vegetable oil is 60-100°C, and the peak intensity ratio (peak intensity at 17Å / peak intensity at 4.0Å) in X-ray diffraction measurement of the coating film is 1.2 or more.

Description

Coated granular fertilizer

[0001] The present invention relates to a coated granular fertilizer.

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

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

[0004] Japanese Patent Application Laid-Open No. 2011-195427

[0005] The present inventors have found 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.

[0006] The present inventors have found that the above problem 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 coating 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] 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 more and 100°C or less, 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 more. [2] 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 more and 100°C or less, and the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.5 Å) of the coating film in X-ray diffraction measurement is 1.5 or more. [3] The coated granular fertilizer according to [1] or [2], wherein the hydrogenated vegetable 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 hydrogenated vegetable oil is hydrogenated castor oil.

[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.

[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, but are not limited to, 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 aforementioned hydrogenated vegetable oil is solid at 25°C. The melting point of the hydrogenated vegetable oil is 60°C to 100°C, and may be 80°C to 90°C. Since hydrogenated vegetable oil with such a melting point can be melted by heating, it can be handled in a liquid state without the use of solvents. Furthermore, using hydrogenated vegetable oil with such a melting point prevents the coated granular fertilizer from sticking to each other or between the coated granular fertilizer and the rotating tank during the production of the coated granular fertilizer, resulting in good manufacturability of the coated granular fertilizer. The manufacturability of the coated granular fertilizer can be measured according to the procedure described in the Examples section below. The freezing point of the hydrogenated vegetable oil is 60°C to 100°C, and may be 80°C to 90°C. Although the melting point and freezing point are generally the same value, in the case of the aforementioned hydrogenated vegetable oil, the melting point may be higher than the freezing point.

[0019] The aforementioned hydrogenated plant oil has low viscosity. By including a hydrogenated plant oil with low viscosity in the coating of the coated granular fertilizer, clumping of the coated granular fertilizers together during manufacturing and storage can be suppressed, resulting in good adhesion of the coated granular fertilizer. The adhesion of the coated granular fertilizer during storage can be measured according to the procedure described in the Examples section below.

[0020] The aforementioned hydrogenated plant oil has lower water vapor permeability compared to biodegradable resins, making it superior in terms of improving the control of leaching of fertilizer components. The aforementioned hydrogenated plant oil has higher fluidity when melted by heating compared to biodegradable resins, which makes it less likely for caking to occur during the production of the coated granular fertilizer, resulting in good manufacturability of the coated granular fertilizer.

[0021] The content of the hydrogenated vegetable 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, but is not limited to these amounts.

[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, but are not limited to, polylactic acid, polyhydroxyalkanoate, polybutylene adipate terephthalate, polycaprolactone, polybutylene succinate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, polyaspartic acid, cellulose fatty acid esters, and polybutylene succinate adipate.

[0024] The coating preferably 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, but are not limited to, 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 (SU-3800, Hitachi High-Tech Corporation) 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 putting the granular urea into a rolling state, a second step of adding the hardened vegetable oil to the rolling 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 an arbitrary temperature.

[0032] In the first step, the heating temperature of the granular urea may be lower than or higher than the melting or freezing point of the hardened vegetable oil. Preferably, the heating temperature of the granular urea is lower than the melting or freezing point of the hardened vegetable oil. The difference between the melting or freezing point of the hardened 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 or freezing point of the hardened vegetable oil and the heating temperature of the granular urea within this range, it is possible to prevent the hardened 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 the difference between the heating temperature of the granular urea and the heating and melting temperature is within this range, thereby preventing 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 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 coated granular fertilizer can be measured according to the procedure described in the Examples section below.

[0035] The coating of the 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 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 17 Å / peak intensity at 4.0 Å) 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 17 Å / peak intensity at 4.5 Å) 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 when the coated granular fertilizer is left standing in a constant temperature chamber set to 54°C for 2 weeks, and then left standing in water at a concentration of 2.5 g / 100 mL (25°C, 2 weeks) is referred to as the elution rate after storage. Leaving it standing at 54°C for 2 weeks is a test condition equivalent to leaving it standing at room temperature for approximately 2 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 value of E2 - E1.

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

[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 Blue Chemical Limited, particle size: approximately 3 mm) [Hydrogenated Vegetable Oils] "Hydrogenated Castor Oil" manufactured by Ito Oil Co., Ltd., melting point 80-90°C (hereinafter referred to as hydrogenated castor oil 1) "Highly Hydrogenated Rapeseed Oil" manufactured by Yokozeki Oil & Fat Industry Co., Ltd., melting point 67°C (hereinafter referred to as highly hydrogenated rapeseed oil) [Petroleum-based Waxes] "HNP-51" manufactured by Nippon Seiro Co., Ltd. (hereinafter referred to as paraffin wax) "Sazole C80" manufactured by Kato Yoko Co., Ltd. (hereinafter referred to as FT wax) [Plant-based Waxes] "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] "Lunaq S-98" manufactured by Kao Chemical Co., Ltd. (hereinafter referred to as stearic acid) 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 Corporation.

[0041] [Example 1] Granular urea 1 (1000 parts by mass) was placed in a rotating tank and turned. The granular urea was heated to approximately 70°C with hot air, then liquid paraffin (MORESCO White P-350P, manufactured by MORESCO Corporation) (10 parts by mass) was added, and the turning state was continued for 5 minutes. The paraffin-coated granular urea was turned, and castor oil 1 (210 parts by mass), which had been heated and melted at 105°C, was added. The turning state was maintained under heating conditions for 3 minutes or more. After that, it was cooled to near room temperature at a cooling rate of 0.4°C / min to obtain coated granular fertilizer (hereinafter referred to as this 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 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 9.0 °C / min (hereinafter referred to as comparative coated granular fertilizer 1).

[0045] [Comparative Examples 2-3] A 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 hardened oil 1 and the heating temperature of the granular urea was 55 °C (hereinafter referred to as comparative coated granular fertilizers 2 and 3, respectively).

[0046] [Comparative Examples 4-5] A 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 hardened oil 1 and the heating temperature of the granular urea was 55 °C (hereinafter referred to as comparative coated granular fertilizers 4 and 5, respectively).

[0047] [Evaluation of the Degradability of Vegetable Hardened Oil, Petroleum Wax, etc.] (Method for Preparing Evaluation Samples) 10 g of samples such as vegetable hardened oil and petroleum wax shown in Table 1 were placed in a thermostat set at 105°C to be melted. The melted samples were cast onto a glass plate using a film applicator (manufactured by All Good Co., Ltd., gap 600 μm), cooled and solidified at room temperature to prepare a film with a film thickness of about 300 μm. (Evaluation Method) 20 g of soil (collection location: Kasai City, Hyogo Prefecture) was placed in a plastic cup (50 mL). The prepared film was cut into pieces of about 2 cm square and 100 mg to prepare test pieces, which were weighed (M1). The test pieces were placed on the soil, and 20 g of soil was added from above. Then, it was lightly tapped on the ground about 10 times for packing. This plastic cup and a water-filled cup for moisture retention were arranged on a tray, put into a plastic bag, and the mouth was lightly tied. It was placed in a thermostat set at 28°C, and the weight of the cup was measured every half month from the start of the test. When a change was observed, it was watered with a spray. After one month, the test pieces were collected, lightly washed, and dried sufficiently at room temperature for one night or more. The mass of the test piece was measured (M2), and the mass reduction rate (W = M2 / M1 × 100 (%)) was calculated. (Evaluation Criteria) A: The mass reduction rate W is 20% or more and less than 40%. B: The mass reduction rate W is 10% or more and less than 20% or 40% or more and less than 60%. C: The mass reduction rate W is less than 10% or 60% or more. When the evaluation is A, it can be evaluated that the degradability as the coating of the coated granular fertilizer is good. The results are shown in Table 1.

[0048]

[0049] [Evaluation of the Manufacturability of Coated Granular Fertilizers] (Evaluation Method) The degree of adhesion between coated granular fertilizers or between a coated granular fertilizer and a rotary tank generated when producing the coated granular fertilizers 1 to 3 and the comparative coated granular fertilizers 1 to 5 of the present invention was visually evaluated. The results are shown in Table 2 and Table 4. (Evaluation Criteria) ○: Almost no adhesion occurred between coated granular fertilizers or between a coated granular fertilizer and a rotary tank. ×: Significant adhesion occurred between coated granular fertilizers or between a coated granular fertilizer and a rotary tank.

[0050]

[0051] [Evaluation of the adhesion properties of coated granular fertilizer during storage] (Evaluation method) 50 g of the coated granular fertilizer 1 was placed in a cylindrical container, and a 5 kg weight was placed on top of it. The container was then left undisturbed in a constant temperature oven 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 coated granular fertilizers 1 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]

[0053] [Dissolution Rate] 2.5 g of the coated granular fertilizer 1 (60-80 granules) was placed in a sample bottle, 100 mL of water was added, and it 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, manufactured by Shimadzu Corporation). Based on the measured urea concentration, the urea dissolution rate E1 (%) from the coated granular fertilizer 1 was calculated. The dissolution rate was similarly evaluated for the 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 and less than 35% C: Dissolution rate E1 is 35% or more If the evaluation is A or B, the dissolution control performance can be evaluated as good.

[0054] [Storage Stability] 2.5 g of the 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, manufactured by Shimadzu Corporation). Based on the measured urea concentration, the elution rate E2 (%) of the coated granular fertilizer 1 after storage was calculated. The elution rate after storage was 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 5% or more and less than 10% C: E2-E1 is 10% or more If the evaluation is A or B, the storage stability can be evaluated as good.

[0055] [Evaluation of XRD Peak Intensity Ratio of Coated Granular Fertilizer Film] The coating of coated granular fertilizer 1 (approximately 100 g) was scratched with a utility knife and immersed in water overnight to dissolve the fertilizer components. After that, it was thoroughly air-dried at room temperature, and the obtained coating was ground in a mortar to obtain a powdered coating sample. Using an XRD (desktop XRD device D2 Phaser, manufactured by BRUKER), CuKα (λ = 1.542 Å) was used as the radiation source, and measurements were taken under the conditions of output 0.3 kW, scanning angle 2θ = 2.0 to 30.0°, and measurement speed 2° / min to obtain the diffraction pattern of the powdered coating sample. The peak intensity ratios (peak intensity at 17 Å / peak intensity at 4.0 Å) and peak intensity ratios (peak intensity at 17 Å / peak intensity at 4.0 Å) of coated granular fertilizers 1 to 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]

Claims

1. A coated granular fertilizer comprising granular urea and a coating film covering the granular urea, wherein the coating film contains a hardened vegetable oil, the melting point of the hardened vegetable 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.

2. A coated granular fertilizer comprising granular urea and a coating film covering the granular urea, wherein the coating film contains a hardened vegetable oil, the melting point of the hardened vegetable oil is 60°C or higher and 100°C or lower, and the peak intensity ratio (peak intensity at 17 Å / peak intensity at 4.5 Å) of the coating film in X-ray diffraction measurement is 1.5 or higher.

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

Images