Coated granular fertilizer

Abstract

The present invention aims to provide a coated granular fertilizer that is biodegradable and has improved manufacturability, elution control, and adhesion during storage. [Solution] The present inventors diligently studied to develop a coated granular fertilizer with improved degradability, manufacturability, elution control, and adhesion during storage. They discovered that by using a plant-derived hydrogenated oil with an iodine value within a specific range as the coating for the coated granular fertilizer, all four characteristics can be simultaneously satisfied, thus completing the present invention.

Description

[Technical Field]

[0001] This invention relates to coated granular fertilizer. [Background technology]

[0002] Coated granular fertilizers have advantages such as controlling the leaching of fertilizer components and allowing their effectiveness to be sustained after a single application, thus reducing the number of applications required.

[0003] For example, Patent Document 1 describes a coated granular fertilizer comprising a resin coating layer provided on the surface of granular urea and a protective layer containing hardened plant oil provided on the outside of the resin coating layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2011-195427 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a coated granular fertilizer that is biodegradable and has improved manufacturability, elution control, and adhesion during storage. [Means for solving the problem]

[0006] The inventors diligently studied to develop a coated granular fertilizer with improved degradability, manufacturability, elution control, and storage adhesion. They discovered that by using a plant-derived hydrogenated oil with an iodine value within a specific range as the coating for the coated granular fertilizer, all four characteristics could be simultaneously satisfied, thus completing the present invention.

[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 iodine value (gI2 / 100g) of the aforementioned hardened plant oil is 35 or less. [2] The hardness of the aforementioned hardened vegetable oil (gf / mm²) 2 A coated granular fertilizer as described in [1], wherein the ratio is 10 or more. [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 has improved manufacturability, elution control, and adhesion during storage. [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 the 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 and 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 and the optional additive and then granulating.

[0015] The coating contains vegetable hardened oil.

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

[0017] The iodine value (gI2 / 100g) of the vegetable hardened oil is 35 or less, may be 25 or less, may be 1 or more and 25 or less, or may be 3 or more and 20 or less. The iodine value of the vegetable hardened oil can be measured according to the procedure described in the Examples section below.

[0018] The hardness (gf / mm 2 ) of the vegetable hardened oil may be 10 or more, or may be 20 or more. The upper limit of the hardness of the vegetable hardened oil is not particularly limited and may be 100 or less, or may be 60 or less. The hardness of the vegetable hardened oil can be measured according to the procedure described in the Examples section below.

[0019] The aforementioned hardened plant oil has moderate decomposition properties in fertilization environments such as soil. The hardened plant oil has a structure similar to that of animal and plant fats and is thought to be decomposed by fat-degrading bacteria that are widely present in the natural environment. Specifically, since the hardened plant oil does not decompose immediately in the fertilization environment, the coating can exhibit elution 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, coated granular fertilizer equipped with a coating containing the hardened plant oil has excellent decomposition and elution control properties. The decomposition properties of the hardened plant oil can be measured according to the procedure described in the Examples section below.

[0020] 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 improved 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 aforementioned hydrogenated vegetable oil is 60°C to 100°C, and may be 80°C to 90°C. While the melting point and freezing point are generally the same, in the case of the aforementioned hydrogenated vegetable oil, the melting point may be higher than the freezing point. The mechanism by which the coated granular fertilizer has good manufacturability is not fully understood, and it is thought that various factors are involved, but one possible mechanism is as follows: The coated granular fertilizer has low tackiness because the iodine value of the hardened plant oil contained in the coating is within a specific range, making it less likely for the coated granular fertilizer to stick together with the rotating tank during manufacturing. This is thought to contribute to the good manufacturability of the coated granular fertilizer.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The mass ratio of the granular fertilizer to the coating may be 1:0.1 or more and 1:0.5 or less.

[0029] 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.

[0030] The method for producing the coated granular fertilizer comprises a first step of putting the granular urea into a rolling state, and a second step of adding the hardened vegetable oil to the rolling granular urea. In the second step, the hardened vegetable oil can be dissolved in a solvent or heated and melted before being added to the granular urea. The method of adding the heated and melted hardened vegetable oil to the granular urea is preferable from the viewpoint of reducing environmental impact because it does not use a solvent. The heating and melting temperature is higher than the melting point of the hardened vegetable oil and may be 70°C, 80°C, 90°C, or 105°C.

[0031] 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.

[0032] 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.

[0033] 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 for 21 days 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.

[0034] The coated granular fertilizer exhibits good dissolution control. The mechanism by which the coated granular fertilizer exhibits good dissolution control is not fully understood, and various factors are thought to be involved, but one possible mechanism is as follows: The iodine value of the hardened plant oil is within a specific range, which results in an appropriate degree of viscosity of the hardened plant oil. This makes the coating less susceptible to damage from contact between the coated granular fertilizers during manufacturing, resulting in the formation of a coating without defects and thus good dissolution control of the coated granular fertilizer.

[0035] The coated granular fertilizer can be spread onto the soil using a spreader such as a side-dressing fertilizer applicator.

[0036] In this specification, the elution rate E2 of the fertilizer components obtained when the coated granular fertilizer is applied using a side-dressing fertilizer applicator (Yanmar Co., Ltd., YK6D), promptly recovered, and then left to stand in water for 21 days in the same manner as described above, is referred to as the elution rate after mechanical application. The E2 of the coated granular fertilizer can be measured according to the procedure described in the Examples section below. The impact resistance of the coated granular fertilizer can be evaluated based on the value of E2-E1. [Examples]

[0037] 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.

[0038] [Granular urea] Granular urea (manufactured by China BlueChemical Limited, particle size: approx. 3mm) [Vegetable hydrogenated oil] Castor oils 1-4 and comparative castor oils 1-3 were prepared using commercially available hydrogenated vegetable oils as raw materials, by adjusting the melting point, iodine value, and hardness to the following values, respectively. Castor oil 1: Melting point 80-90°C, iodine value 3g I2 / 100g, hardness 59gf / mm 2 Castor oil 2: Melting point 80-90°C, iodine value 8g I2 / 100g, hardness 39gf / mm2 Castor hardened oil 3: melting point 80 - 90°C, iodine value 14 g I2 / 100 g, hardness 27 gf / mm 2 Castor hardened oil 4: melting point 80 - 90°C, iodine value 20 g I2 / 100 g, hardness 24 gf / mm 2 Comparative castor hardened oil 1: melting point 80 - 90°C, iodine value 37 g I2 / 100 g, hardness 7 gf / mm 2 Comparative castor hardened oil 2: melting point 80 - 90°C, iodine value 48 g I2 / 100 g, hardness 2 gf / mm 2 Comparative castor hardened oil 3: melting point 80 - 90°C, iodine value 59 g I2 / 100 g, hardness 0.7 gf / mm 2 "Rapeseed extremely hardened oil" manufactured by Yokose Oil & Fat Industry Co., Ltd., melting point 67°C (hereinafter referred to as rapeseed extremely hardened oil). [Petroleum wax] "HNP - 51" manufactured by Nippon Seiro Co., Ltd. (hereinafter referred to as paraffin wax). "Sasol C80" manufactured by Kato Yoko Co., Ltd. (hereinafter referred to as FT wax). [Plant 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" manufactured by Kao Chemical Co., Ltd. (hereinafter referred to as stearic acid). "Nissan Electol WEP - 5" manufactured by NOF Corporation (hereinafter referred to as fatty acid ester). "Calcohol 220 - 80" manufactured by Kao Chemical Co., Ltd. (hereinafter referred to as behenyl alcohol).

[0039] [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 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. After that, it was cooled to near room temperature to obtain coated granular fertilizer (hereinafter referred to as coated granular fertilizer 1).

[0040] [Example 2] A coated granular fertilizer was obtained in the same manner as in Example 1, except that castor oil 2 was used instead of castor oil 1 (hereinafter referred to as "Coated Granular Fertilizer 2").

[0041] [Example 3] A coated granular fertilizer was obtained in the same manner as in Example 1, except that castor oil 3 was used instead of castor oil 1 (hereinafter referred to as "this coated granular fertilizer 3").

[0042] [Example 4] A coated granular fertilizer was obtained in the same manner as in Example 1, except that castor oil 4 was used instead of castor oil 1 (hereinafter referred to as "this coated granular fertilizer 4").

[0043] [Comparative Example 1] A coated granular fertilizer was obtained in the same manner as in Example 1, except that comparative castor hydrogenated oil 1 was used instead of castor hydrogenated oil 1 (hereinafter referred to as comparative coated granular fertilizer 1).

[0044] [Comparative Example 2] A coated granular fertilizer was obtained in the same manner as in Example 1, except that comparative castor hydrogenated oil 2 was used instead of castor hydrogenated oil 1 (hereinafter referred to as comparative coated granular fertilizer 2).

[0045] [Comparative Example 3] A coated granular fertilizer was obtained in the same manner as in Example 1, except that comparative castor hydrogenated oil 3 was used instead of castor hydrogenated oil 1 (hereinafter referred to as comparative coated granular fertilizer 3).

[0046] [Comparative Examples 4-5] Coated granular fertilizers were obtained in the same manner as in Example 1, except that FT wax or carnauba wax was used instead of castor oil 1 (hereinafter referred to as comparative coated granular fertilizer 4 or 5, respectively).

[0047] [Comparative Examples 6-7] Coated granular fertilizer was obtained in the same manner as in Example 1, 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 referred to as comparative coated granular fertilizer 6 or 7, respectively).

[0048] [Evaluation of the iodine value of hydrogenated vegetable oils] The iodine values ​​of castor hydrogenated oils 1-4 and comparative castor hydrogenated oils 1-3 were measured in accordance with "JIS K 0070:1992 Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products".

[0049] [Evaluation of the hardness of hydrogenated vegetable oils] Castor oil 1 was heated and melted at 105°C, poured into a silicone mold, and allowed to solidify at room temperature to prepare a particulate test sample with a particle size of approximately 7 mm. A particle hardness analyzer (New Grano, manufactured by Okada Seikou Co., Ltd.) was used to apply stress to the test sample until a crack occurred. A crack was determined to have occurred in the test sample when the stress decreased by 10% during the test, or when fracture of the test sample was visually confirmed, whichever came first. The maximum stress value (gf) at the time of cracking was obtained. The particle size (mm) of the test sample was defined as the displacement of the jig from the bottom surface when the stress first exceeded 0.06 kgf. The hardness was calculated by substituting the maximum stress value (gf) and the particle size (mm) into the following formula 1. Hardness was calculated for 5 or more test samples, and the average value was defined as the hardness. The hardness of castor hydrogenated oils 2-4 and comparative castor hydrogenated oils 1-3 was measured using the same procedure.

[0050] [Mathematics 1] Hardness = ((2.8 × maximum stress) / (π × grain size) 2 ))

[0051] [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.

[0052] [Table 1]

[0053] [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 1-4 and comparative coated granular fertilizers 1-3 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.

[0054] [Table 2]

[0055] [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.

[0056] [Table 3]

[0057] [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 sample was left to stand at 25°C. After 21 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. E1 was similarly calculated 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 15% B: Dissolution rate E1 is 15% or more but less than 30% C: Dissolution rate E1 is 30% or higher Dissolution control can be evaluated as good if the evaluation is A or B.

[0058] [Impact Resistance] This coated granular fertilizer 1 was spread using a side-dressing fertilizer applicator (Yanmar Co., Ltd., YK6D) and then collected. The collected coated granular fertilizer 1 (2.5g, 60-80 granules) was placed in a sample bottle, 100mL of water was added, and it was left to stand at 25°C. After 21 days, the urea concentration was measured using the same method as above. Based on the measured urea concentration, the elution rate E2 (%) after mechanical application was calculated. E2 was calculated similarly for coated granular fertilizer 3. Impact resistance was evaluated based on the E2-E1 value. The results are shown in Table 4. (Evaluation Criteria) A: E2-E1 is less than 20% B: E2-E1 is between 20% and less than 30% C:E2-E1 is over 30% A rating of A or B indicates good impact resistance.

[0059] [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. The iodine value (gI) of the aforementioned hydrogenated vegetable oil 2 Coated granular fertilizer with a content of 35 or less per 100g.

2. The hardness (gf / mm) of the aforementioned hydrogenated vegetable oil 2 The coated granular fertilizer according to claim 1, wherein the number of ) is 10 or more.

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 aforementioned hardened plant oil is hardened castor oil.

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