JP6671327B2 - Method for producing granular oxamide - Google Patents

Description

  The present invention relates to a method for producing granular oxamide, and more particularly to a method for producing granular oxamide having high fertilizer hardness and high disintegration resistance in water or soil, and having stable slow-release fertilization.

One of the characteristics of the change in agricultural structure from 2010 to 2015 is that the number of farms managed and the number of farmers sold decrease at a record high, and the aging of agricultural workers is increasing. For this reason, slow-release nitrogen-containing fertilizers are widely used at farm sites where the physical load of fertilization work is as small as possible and the number of times of topdressing is small. Oxamide [(CONH ₂ ) ₂ ] is one of the representative examples, and is used as an odorless white powder which is excellent as a slow-release nitrogen fertilizer with low solubility in water and no phytotoxicity to crops. I have.

  However, powdered oxamide is mineralized relatively quickly by microorganisms in the soil (meaning that oxamide is decomposed to a form that can be absorbed by plants), and the nitrogenized mineral components are ammonium sulfate, urea, and salt ammonium. As with nitrogenous fertilizers that are easily soluble in water, such as ammonium nitrate, loss due to erosion and the like is likely to occur, so that the slow-release characteristics of oxamide cannot be fully exhibited. Further, even if oxamide is kneaded and contained in the chemical fertilizer, the fertilizer particles are rapidly disintegrated under the flooded condition, so that the microorganisms involved in the decomposition rapidly decompose and cannot exert a slow-release fertilizer effect.

  In general, by controlling the dissolution of oxamide into water and soil to suppress contact between oxamide and microorganisms that degrade oxamide, reduce the rate of mineralization of oxamide and slow down the fertilizing effect of oxamide. Is possible. In order to control the dissolution of oxamide into water or soil, it is necessary to make the particle strength as high as possible and to make the particles hard to disintegrate in water or soil.

  As a granulation accelerator (binder) for fertilizer granulation, bentonite, molasses, lignin sulfonate, starch, konjac flour, sodium alginate, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyacrylamide (PAM) ), Gypsum, sodium humate and the like are known (Non-Patent Document 1).

  By using these, the particle strength of the fertilizer particles containing oxamide and the property that the particles are maintained in shape without disintegration in water (shape stability in water) are improved to control the elution and to improve the oxamide and its properties. As a technique aimed at suppressing contact with microorganisms involved in decomposition, oxamide powder is combined with polyvinyl alcohol, extruded into a rod shape, and then granulated (Patent Document 1). Oxamide powder is combined with polyvinyl alcohol. After extrusion molding into a rod shape, granulation, the granulated product is deformed into a spherical shape by a high-speed rolling granulator (Patent Document 2), oxamide and iron compounds such as iron sulfate, iron chloride, iron nitrate, and phosphoric acid A composition containing an ammonium salt of phosphoric acid such as monoammonium is granulated with a dish granulator, an extrusion granulator or the like (Patent Document 3), oxamide, gypsum, and aluminum sulfate A composition containing an aluminum compound such as aluminum, aluminum chloride and aluminum nitrate and an ammonium phosphate such as ammonium phosphate is granulated by a dish granulator, an extrusion granulator or the like (Patent Document 4), oxamide and ammonium chloride It is disclosed that a fertilizer is made by adding diammonium phosphate, gypsum and granulating with a dish granulator, an extrusion granulator or the like (Patent Document 5).

  Further, Patent Document 6 discloses that polyvinyl alcohol having a degree of polymerization of 1800 or less and a saponification degree of 90 mol% or less and a raw material fertilizer (specifically, a processed ore phosphate fertilizer, an ore oxyacid fertilizer, a mixed phosphate fertilizer, a chemical fertilizer, Fertilizer) and granulate with a dish granulator to provide a granular fertilizer having a high particle strength, and particularly excellent in disintegration in water at low temperatures.

  However, the method of Patent Document 1 has a problem that the hardness of granular oxamide is as low as 2 kgf or less, and powdering occurs in the bag after molding. In the method of Patent Document 2, the hardness of the spherical oxamide is as low as 3 kgf or less, and in order to make it spherical, it is mixed with a twin-screw rotor type mixer, extruded, and further formed as a high-speed rolling granulator. Production with two or more types of devices using a marmalizer manufactured by Powdal Co., Ltd. is required. Further, in the methods of Patent Documents 3, 4, and 5, the hardness of the granular fertilizer is as high as 5 to 9 kgf, but the ratio of the additive to the powdery oxamide is high, so that the amount of nitrogen derived from oxamide in the granular fertilizer is reduced. was there. In addition, regarding the underwater shape stability which is directly linked to the stable slow-release fertilization effect of granular oxamide, the results are as short as 2 weeks in Patent Document 1, 1 hour in Patent Documents 3 and 4, and 10 hours in Patent Document 5. It is not sufficient as a slow-release fertilizer in water or soil under flooded conditions. Further, Patent Document 6 is a technique for providing a granular fertilizer excellent in disintegration in water, which is different from the granular oxamide which is not easily disintegrated in water and aimed at in the present invention.

  Patent Literature 7 discloses a coated nitrification-suppressing material-mixed fertilizer obtained by mixing a coated nitrification-suppressing material obtained by coating a nitrification inhibitor with a coating material and a fertilizer containing ammonium nitrogen and / or urea nitrogen. As an example of a granulation method for producing, a method of adding a nitrification inhibitor, a powder of a fertilizer, and the like to an inclined bread type granulator, granulating the aqueous solution of lignin sulfonate, molasses as a binder, and extruding. A method using a granulator, a method using a mixed granulator such as an Erich mixer, and the like are described.

  Patent Literature 8 discloses a granular nitrification-inhibiting material obtained by mixing and granulating a nitrification inhibitor and a diluent (excluding a chemical fertilizer and a urea containing a nitrate nitrogen and an ammonia nitrogen as a nitrogen component). As an example of a granulation method for producing a coated nitrification control material obtained by coating a coating material with a coating material, as an example of a granulation method, a powder such as a nitrification inhibitor and a chemical fertilizer is put into an inclined pan type granulator. Further, a method of granulating an aqueous solution of lignin sulfonate, molasses, etc. as a binder, a method of using an extrusion granulator, a method of using a mixed granulator such as an Erich mixer, and the like are described.

  However, a graded Erich mixer has never been used in the production of oxamide granulation.

JP-A-59-169527 JP-A-2-145493 Japanese Patent Publication No. 6-2628 Japanese Patent Publication No. 6-2629 Japanese Patent Publication No. 6-2630 JP 2006-21968 A JP-A-2000-53481 (Claim 1, Paragraph 0011, Production Examples 1 and 6) JP-A-2000-53482 (Claim 1, Paragraph 0014, Production Examples 1 and 2)

"Fertilizer processing science" Granulation accelerator (binder) BSI Institute for Biological Sciences

  An object of the present invention is to provide a granular oxamide having high fertilizer hardness, high resistance to disintegration in water and soil, and a stable slow-release fertilizer effect.

  The present inventors have conducted intensive studies to solve the above-described problems, and as a result, by adding polyvinyl alcohol or modified polyvinyl alcohol to oxamide, granulating by high-speed stirring and drying in an inclined type mixing pan container, The present inventors have found that fertilizer hardness is high, and that particle shape stability can be kept high even under flooded conditions and field conditions, and the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) A mixture containing 0.5 parts by weight or more of polyvinyl alcohol or modified polyvinyl alcohol with respect to 100 parts by weight of oxamide powder is subjected to high-speed stirring granulation in an inclined mixing pan container, and then dried. For producing granular oxamides.
(2) a mixing pan that rotates, a mixing tool that is arranged at a position eccentric from the center position of the mixing pan and that rotates independently of the mixing pan, and a scraper that is fixed and disposed inside the mixing pan. The production method according to (1), wherein high-speed stirring granulation is performed using a high-speed stirring mixer provided with
(3) The production method according to the above (2), wherein the time of high-speed stirring granulation after the addition of polyvinyl alcohol or modified polyvinyl alcohol and water is 13 to 60 minutes.

  According to the present invention, the fertilizer hardness is high, the disintegration resistance in water and soil is high, by providing a granular oxamide that can exert a stable slow-release fertilizer effect, reduce the number of top fertilization during crop cultivation This makes it possible to reduce the burden on fertilizer application due to the aging of agricultural workers in recent years.

FIG. 1 is a schematic perspective view showing one example of a high-speed stirring mixer used when carrying out the present invention. FIG. 2 is a diagram showing the results of a mineralization test at 25 ° C. under paddy field conditions.

  The polyvinyl alcohol or modified polyvinyl alcohol used in the present invention has a polymerization degree of 1300 to 2400, a viscosity (mPa · S) of 15 to 50, a saponification degree (mol%) of 90 or more, and preferably a polymerization degree of 1700 to 1700. 1800, a viscosity (mPa · S) of 20 to 30, and a saponification degree (mol%) of 98.0 to 99.7 are preferable, but not limited to this range.

  Although there is no particular limitation on the modified polyvinyl alcohol, for example, acid-modified polyvinyl alcohol (hereinafter, also referred to as “acid-modified PVA”), ethylene-modified polyvinyl alcohol, and the like can be used.

  The acid-modified PVA is a vinyl alcohol-based polymer containing a predetermined amount of a carboxy group or a sulfonic acid group. The former is called a carboxylic acid-modified PVA, and the latter is called a sulfonic acid-modified PVA.

  The carboxylic acid-modified PVA can be produced by introducing a compound having a carboxy group into polyvinyl alcohol by a conventionally known method. Examples of the compound containing a carboxy group include fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimetic anhydride, acrylic acid, and salts thereof.

  The sulfonic acid-modified PVA can be produced by introducing a compound having a sulfonic acid group into polyvinyl alcohol by a conventionally known method. Examples of the compound having a sulfonic acid group include ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof.

  Ethylene-modified polyvinyl alcohol is obtained by saponifying a copolymer of vinyl ester and ethylene, and examples of vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, and vinyl pivalate.

  The content of polyvinyl alcohol or modified polyvinyl alcohol in the granular oxamide of the present invention is 0.5 parts by weight or more, preferably 1 to 10 parts by weight, based on 100 parts by weight of the oxamide powder, from the viewpoint of ensuring particle hardness and shape stability in water. Parts by weight, more preferably 1 to 2 parts by weight. When the content of the polyvinyl alcohol or the modified polyvinyl alcohol is less than 0.5 part by weight, the effect as a binder during granulation is weak, and the effect of increasing the particle hardness after granulation is low. The nitrogen component of oxamide is reduced, and the quality of the component is reduced.

Next, a preferred embodiment of the method for producing a granular oxamide of the present invention will be described.
First, polyvinyl alcohol or modified polyvinyl alcohol is dissolved in the following manner. Measured polyvinyl alcohol or denatured polyvinyl alcohol is gradually added while stirring the room-temperature water, and heating is started while stirring is continued. After the liquid temperature reaches 90 to 95 ° C, stirring is continued for 1 to 2 hours while maintaining the temperature. Thereafter, the heat source is turned off, the stirring power is reduced, and the mixture is gradually cooled to prepare an aqueous solution of polyvinyl alcohol or a modified polyvinyl alcohol having a certain concentration. The concentration of the polyvinyl alcohol or the modified polyvinyl alcohol solution is not particularly limited, but a 10 to 15% solution is suitable for the viscosity in handling and the amount to be added during fertilizer production. Next, a polyvinyl alcohol or a modified polyvinyl alcohol solution prepared by dissolution is gradually added so as to have a weight ratio of 0.5 part by weight or more with respect to 100 parts by weight of the oxamide powder put in the granulator, and an inclined mixing pan is prepared. High-speed stirring granulation is performed in a container, and the granulated product is dried. The polyvinyl alcohol or modified polyvinyl alcohol to be added to the oxamide powder is desirably added in a liquid state in order to make the bonding force between the raw material powders uniform, but may be added in a powdery form when the addition amount is small. Further, in addition to the oxamide powder, a mineral powder or the like may be added for adjusting the bulk specific gravity or preventing floating in water.

  The granulator used for granulation is a high-speed stirring granulator having an inclined mixing pan container (hereinafter, referred to as an inclined Erich mixer) manufactured by Eich Co., Ltd. The details of which are described in Japanese Patent No. 4406328. No., granulation by a high-performance mixer characterized by high density and high production, "Basic and Application of Powder Technology", Sep. Issue of Chemical Apparatus, Vol.

  FIG. 1 is a schematic perspective view showing one example of a high-speed stirring mixer used when carrying out the present invention. As shown in FIG. 1, a high-speed stirring mixer 1 used in the present invention accommodates an object to be agitated, and a mixing pan 2 that rotates while accommodating the object to be agitated, and a mixing pan 2 inside the mixing pan 2. A mixing tool (also referred to as an “agitator”) 3 that is arranged at a position eccentric from the center position of the pan 2 and rotates independently of the mixing pan 2, and a scraper 4 fixed and arranged inside the mixing pan 2 It has. The mixing pan 2 and the mixing tool 3 can set the rotation direction and the rotation speed independently of each other. The mixing direction of the mixing pan 2 and the mixing tool 3 can be set to the opposite direction. When the rotation direction with the tool 3 is set to the same direction, the stirring can be performed by two types of stirring methods.

  The outline of the operation procedure is as follows. After feeding the fertilizer raw material into the device, the peripheral speed of the rotor is increased (usually 1 to 10 m / s, preferably 2 to 6 m / s) and mixed to homogenize the raw material. Next, a polyvinyl alcohol or modified polyvinyl alcohol liquid and added water are added. The peripheral speed of the rotor is increased (usually 10 to 40 m / s, preferably 15 to 35 m / s) to perform dispersion and granulation. The time for high-speed stirring and granulation after the addition of polyvinyl alcohol or modified polyvinyl alcohol and water is preferably 13 minutes or more from the viewpoint of the production rate of the target particle size, and it is possible to prevent a large agglomeration state due to adhesion of the particles. It is preferably 60 minutes or less from the point of view. The time for the high-speed stirring granulation is further preferably 15 to 45 minutes, and more preferably 20 to 45 minutes. Thereafter, the peripheral speed of the rotor is reduced to perform a treatment of 1 to 10 m / s, preferably 2 to 6 m / s), and finally, the mixture is discharged from the mixer. The obtained granules are dried by heating in a dryer to produce granulated oxamide. The drying temperature is usually 65 to 130 ° C, preferably 90 to 120 ° C.

  The shape and size of the granular oxamide of the present invention are not particularly limited, but are usually granular having a particle size in the range of 1 to 10 mm. In particular, those having a particle size in the range of 2 to 4 mm are preferable because they have good workability such as scattering of fertilizer can be reduced. In addition, even when the granulated composition according to the present invention is blended with other chemical fertilizers, classification is small and good.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
As the polyvinyl alcohol (PVA) or the modified polyvinyl alcohol (modified PVA), those having a pure content of 94.00% or more were used. The amount (%) of addition was shown by weight ratio to the oxamide powder.

(Example 1) Production of granular oxamide containing 1% of modified PVA using a tilted Erich mixer A 5 L beaker containing 2.7 parts by weight of water was immersed in a water bath at normal temperature, and a stirring motor was set to stir the water. 0.3 parts by weight of modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., degree of polymerization 1300, degree of saponification 92 to 98) was gradually added. After the mixture was heated with stirring to reach 95 ° C., the mixture was stirred for 2 hours while maintaining the temperature. After confirming that the modified PVA was completely dissolved, the stirring power was reduced and the mixture was gradually cooled to prepare a 10% liquid.
20 parts by weight of the oxamide powder was put into a mixing pan container of an inclined Erich mixer (manufactured by Nippon Erich Co., Ltd., Intensive Mixer R02; the same applies hereinafter), and 2 parts by weight of the prepared modified PVA 10% solution was added thereto. The mixing was performed at a peripheral speed of 6 m / s (900 rpm) for 1 minute and 15 seconds. Next, 3.53 parts by weight of water was added, and dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, and the peripheral speed of the rotor was reduced to 6 m / s (900 rpm) for 1 minute and 30 seconds. After that, it was discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing 1% of modified PVA.

Example 2 Production of Granular Oxamide Containing 2% PVA Using Inclined Erich Mixer A 10 L beaker containing 5.4 parts by weight of water was immersed in a normal temperature water bath, and a stirring motor was set to stir the water. 0.6 parts by weight of PVA was gradually added. After the mixture was heated with stirring to reach 95 ° C., the mixture was stirred for 2 hours while maintaining the temperature. After confirming that PVA was completely dissolved, the stirring power was reduced and the mixture was gradually cooled to prepare a 10% liquid.
After 20 parts by weight of the oxamide powder was charged into a mixing pan container of an inclined Erich mixer, 4 parts by weight of the prepared PVA 10% liquid was added, and the mixture was mixed for 1 minute at a peripheral speed of a rotor of 6 m / s (900 rpm). Further, 1.66 parts by weight of water was added, and dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 21 minutes, and the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), and the mixture was treated for 2 minutes. Discharged. The discharged granular product was dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a 2% PVA-containing granular oxamide.

Example 3 Production of Granular Oxamide Containing 1% PVA Using a Tilt-Type Erich Mixer After 20 parts by weight of oxamide powder was charged into a mixing pan container of a tilt-type Ericht mixer, 2 parts by weight of a 10% PVA liquid prepared in Example 2 was used. The mixture was added and mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute. Further, 3.63 parts by weight of water was added, and the dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 22 minutes, and the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), followed by treatment for 2 minutes. Discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours and then sieved to a particle size range of 2 to 4 mm to obtain a 1% PVA-containing granule oxamide.

(Example 4) Production of granular oxamide containing 4% of modified PVA using an inclined Erich mixer A 10 L beaker containing 4.8 parts by weight of water was immersed in a water bath at room temperature, and a stirring motor was set to stir the water. 1.2 parts by weight of the modified polyvinyl alcohol was gradually added while adding. After the mixture was heated with stirring to reach 95 ° C., the mixture was stirred for 2 hours while maintaining the temperature. After confirming that the modified PVA was completely dissolved, the stirring power was reduced and the mixture was gradually cooled to prepare a 20% liquid.
After 20 parts by weight of the oxamide powder was charged into a mixing pan container of an inclined Erich mixer, 4 parts by weight of the prepared 20% modified PVA solution was added, and mixed at a peripheral speed of a rotor of 6 m / s (900 rpm) for 1 minute. Further, 2.3 parts by weight of water was added, and dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 18 minutes, and the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), followed by treatment for 2 minutes. Discharged. The discharged granular product was dried in a dryer at 105 ° C for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing modified PVA 4%.

(Example 5) Production of granular oxamide containing 0.5% of modified PVA using inclined Erich mixer 20% by weight of oxamide powder was charged into a mixing pan container of an inclined Erich mixer, and then a 10% modified PVA liquid prepared in Example 1 was added. Was added and mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute and 15 seconds. Next, 4.4 parts by weight of water is added, and dispersion / granulation is performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, and the peripheral speed of the rotor is reduced to 6 m / s (900 rpm) for 1 minute and 30 seconds. After that, it was discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granulated oxamide containing 0.5% of modified PVA.

Example 6 Production of Granular Oxamide Containing 0.5% PVA Using Inclined Erich Mixer After 20 parts by weight of oxamide powder was charged into a mixing pan container of an inclined Erich mixer, a 10% PVA solution prepared in Example 2 was added to 1 part. Parts by weight were added and mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute and 15 seconds. Next, 4.4 parts by weight of water is added, and dispersion / granulation is performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, and the peripheral speed of the rotor is reduced to 6 m / s (900 rpm) for 1 minute and 30 seconds. After that, it was discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a particulate oxamide containing 0.5% PVA.

(Comparative Example 1) Production of granular oxamide containing 1% of modified PVA using a horizontal Erich mixer After 20 parts by weight of oxamide powder was put into a mixing pan container of a horizontal Erich mixer (manufactured by Nippon Erich Co., Ltd., intensive mixer DE14). Then, 2 parts by weight of the modified PVA 10% liquid prepared in Example 1 was added and mixed for 1 minute at a peripheral speed of the rotor of 13 m / s (600 rpm). Further, 3.65 parts by weight of water was added, and dispersion / granulation was performed at a peripheral speed of the rotor of 31 m / s (1500 rpm) for 25 minutes, and the peripheral speed of the rotor was reduced to 13 m / s (600 rpm), followed by treatment for 2 minutes. Discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing 1% of modified PVA.

(Comparative Example 2) Production of granular oxamide containing 1% of modified PVA using a dish-shaped granulator 20% by weight of oxamide powder was breaded by a dish-shaped granulator (a motor-driven self-made bread granulator manufactured by Sumitomo Heavy Industries, Ltd.). After charging into the container, 2 parts by weight of the modified PVA 10% liquid prepared in Example 1 was added and mixed at a peripheral speed of bread of 1.6 m / s (40 rpm) for 15 minutes. Further, while gradually adding 8.02 parts by weight of water, granulation was performed at a peripheral speed of the bread of 1.6 m / s (40 rpm) for 30 minutes. The granulated product was dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing 1% of modified PVA.

Comparative Example 3 Production of Granulated Oxamide Containing 1% Modified PVA by Extrusion Granulator 20 parts by weight of powdered oxamide was charged into a twin-screw rotor type mixer (manufactured by Fuji Paudal Co., Ltd.), and then modified in Example 1. 2 parts by weight of a PVA 10% liquid and 6.46 parts by weight of water were added and kneaded sufficiently.
The kneaded material was put into a screw extrusion granulator (manufactured by Fuji Paudal Co., Ltd., screen mesh 1.2 mm), and extruded and granulated. The granulated product extruded from the screen was dried in a dryer at 105 ° C. for 24 hours and then cut into a length of 0.5 to 1 cm to obtain a granular oxamide containing 1% of modified PVA in pellet form.

Comparative Example 4 Production of Granular Oxamide (No Granulation Accelerator Added) Using Inclined Erich Mixer After charging 20 parts by weight of oxamide powder into a mixing pan container of an inclined Erich mixer, 3.81 parts by weight of water was added. Then, mixing was performed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute. Further, 1.82 parts by weight of water was added, and the dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 32 minutes, and the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), followed by treatment for 2 minutes. Discharged. The discharged granular product was dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide.

(Comparative Example 5) Production of granular oxamide containing 2% starch by using an inclined Erich mixer After charging 20 parts by weight of oxamide powder and 0.4 part by weight of starch into a mixing pan container of an inclined Erich mixer, the peripheral speed of a rotor is 6 m. / S (900 rpm) for 1 minute. Next, 5.1 parts by weight of water was added and mixed for 1 minute at a peripheral speed of the rotor of 6 m / s (900 rpm). Further, the dispersion / granulation was performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 25 minutes, the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), and the mixture was discharged for 2 minutes. The discharged granular product was dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing 2% starch.

(Comparative Example 6) Production of granular oxamide containing 2% of carboxymethylcellulose (CMC) using an inclined Erich mixer After 20 parts by weight of oxamide powder and 0.4 part by weight of CMC were charged into a mixing pan container of an inclined Erich mixer, The mixture was mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute. Next, 5.1 parts by weight of water was added and mixed for 1 minute at a peripheral speed of the rotor of 6 m / s (900 rpm). Further, the dispersion and granulation were performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, the peripheral speed of the rotor was reduced to 6 m / s (900 rpm), and the mixture was discharged for 2 minutes. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain granulated oxamide containing 2% of CMC.

Comparative Example 7 Production of Granular Oxamide Containing Mineral, Iron Sulfate, and Phosphoric Acid Using Inclined Erich Mixer 20 parts by weight of oxamide powder and 1.25 parts by weight of mineral (basalt powder), 0.42 parts by weight of iron sulfate, phosphoric acid After 2.5 parts by weight of the liquid was put into a mixing pan container of an inclined Erich mixer, the mixture was mixed for 1 minute at a peripheral speed of a rotor of 6 m / s (900 rpm). Next, 3.11 parts by weight of water was added and mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute. Further, dispersion / granulation was carried out at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 15.5 minutes, the peripheral speed of the rotor was lowered to 6 m / s (900 rpm), and the mixture was discharged for 2.75 minutes and then discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a range of particle diameter of 2 to 4 mm, to obtain granulated oxamide containing iron sulfate and phosphoric acid.

(Comparative Example 8) Production of granular oxamide containing 0.2% of modified PVA using inclined Erich mixer 20% by weight of oxamide powder was put into a mixing pan container of inclined Erich mixer, and then a modified PVA 10% liquid prepared in Example 1 was added. Was added and mixed at a peripheral speed of the rotor of 6 m / s (900 rpm) for 1 minute and 15 seconds. Next, 4.88 parts by weight of water is added, and dispersion / granulation is performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, and the peripheral speed of the rotor is reduced to 6 m / s (900 rpm) for 1 minute and 30 seconds. After that, it was discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granulated oxamide containing modified PVA 0.2%.

(Comparative Example 9) Production of granular oxamide containing 0.2% of PVA using an inclined Erich mixer After 20 parts by weight of oxamide powder was charged into a mixing pan container of an inclined Erich mixer, the PVA 10% liquid prepared in Example 2 was mixed with 0%. And then mixed for 1 minute and 15 seconds at a peripheral speed of the rotor of 6 m / s (900 rpm). Next, 4.88 parts by weight of water is added, and dispersion / granulation is performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 23 minutes, and the peripheral speed of the rotor is reduced to 6 m / s (900 rpm) for 1 minute and 30 seconds. After that, it was discharged. The discharged granular product was dried in a dryer at 105 ° C. for 4 hours, and then sieved to a particle size range of 2 to 4 mm to obtain a granular oxamide containing 0.2% PVA.

(Evaluation test 1)
Each of the granular oxamides obtained in Examples 1 to 6 and Comparative Examples 1 to 9 was examined for hardness and shape stability in water as an evaluation as a slow-release nitrogenous fertilizer. The test methods are as follows. In the tests described below, among the obtained granular fertilizers, those having a particle size in the range of 2.85 to 3.50 mm were selected and used.
Moisture: The obtained granular oxamide is pulverized with a pulverizer, accurately measure about 5 g of the powder passed through a 0.5 mm sieve, dried in a dryer at 105 ° C. for 3 hours, and the reduced weight is divided by the sample weight. And multiplied by 100. The results are shown in Tables 1, 2 and 3.
Hardness: The particle hardness of 20 granular oxamide particles was measured using a Kiya hardness meter, and the results are shown in Tables 1, 2, and 3.
Underwater shape stability: After 20 granules of oxamide are charged into a Mericlon tube bottle containing 50 ml of water, the state of grain surface collapse is observed in a thermostat at 25 ° C., immediately after pouring, 3 days and 14 days later , 28 and 56 days later. The disintegration state is 0: no disintegration, 1: 10% or less of disintegration of the grain surface, 2: 11 to 30% of disintegration of the grain surface, 3: 31 to 50% of disintegration of the grain surface, 4: 51 to 70 of the disintegration of the grain surface %, 5: Disintegration of grain surface 71 to 90%, 6: Disintegration of grain surface 91 to 100%, and shown in Tables 1, 2 and 3.

  As shown in the results shown in Table 1, in the method using the granulating apparatus of Comparative Examples 1 to 3, the fertilizer particle hardness was 3.1 kgf or less, whereas Example 1 was 6.3 kgf. By the method of the invention, a granular oxamide having high hardness could be produced.

  Further, regarding the shape stability in water, in Comparative Examples 1 to 3, the disintegration of the grain surface started immediately after water injection and 31% or more of the grain surface disintegrated after 56 days, whereas in Example 1, the disintegration was also occurred after 56 days. I couldn't see it.

Table 2 shows the results of comparison of the granulation accelerators using the inclined Erich mixer.
The fertilizer particle hardness of Comparative Example 4 without the addition of a granulation accelerator was 3 kgf or less. In Comparative Examples 5 and 6, the weight was 5.3 and 4.5 kgf, which was lower than that in Example 2. In Comparative Example 7, 6.6 kgf was not much different from Example 2.

  However, regarding the shape stability in water, in Comparative Example 4, no disintegration of the particle surface was observed immediately after water injection, but after 3 days, disintegration proceeded, and after 56 days, 51% or more of the particle surface disintegrated. In Comparative Examples 5, 6, and 7, although the hardness was higher than Comparative Example 4, the disintegration of the grain surface started immediately after water injection, and after 56 days, 51% or more of the grain surface disintegrated. In contrast, Example 2 did not disintegrate after 56 days.

  As shown in Table 3, Comparative Examples 8 and 9, in which the amount of PVA or modified PVA added was 0.2%, had a fertilizer grain hardness of 2.8 kgf, and the shape stability in water also showed collapse immediately after water injection. Was done. On the other hand, in Examples 1 to 6 in which the amount of PVA or modified PVA added was 0.5% or more, the hardness was 4.5 kgf or more, and the shape stability in water was also high.

  As described above, according to the method of the present invention, a granular oxamide having a high hardness, in particular, being hardly disintegrated in water and having a high shape stability was able to be produced.

(Evaluation test 2: mineralization test under 25 ° C, paddy field conditions)
(1) Purpose Paddy field conditions of granular oxamide containing 1% of modified PVA manufactured by an inclined Erich mixer (Example 1) and granular oxamide containing mineral, iron sulfate, and phosphoric acid manufactured by an inclined Erich mixer (Comparative Example 7). Consider mineralization in
(2) Test Method 60 g of dry soil [Tsukuba paddy soil (sandy loam)] was mixed with test oxamide-containing fertilizer granules (four granules corresponding to 24 mg as nitrogen) and placed in a 200 ml beaker. As for phosphoric acid and potassium, 12 mg per 60 g of dry soil was added as a component with monopotassium phosphate and potassium chloride. Next, after adding deionized water so that it might become 140% of the maximum capacity of the test soil, and covering with a polyethylene film, it left still in a 25 ° C constant-temperature oven for a predetermined period.
After a lapse of a predetermined period, the sample in the beaker was filtered by shaking with 300 ml of a 10% aqueous potassium chloride solution, and inorganic nitrogen (the total amount of NH ₄ and NO ₃ ) was quantified by the Conway method to calculate the mineralization rate.
(3) Results The results are shown in Table 4 and FIG.

As can be seen from Table 4 and FIG. 2, the granular oxamide containing 1% of modified PVA produced by the inclined Erich mixer has a lower mineralization than the particulate oxamide containing mineral, iron sulfate, and phosphoric acid produced by the inclined Erich mixer. Late, slow-release fertilization was exhibited.
That is, the granular oxamide containing 1% of modified PVA, which is a product of the present invention, has a small difference in hardness, but has a high shape stability in water, and has a low hardness, as compared with the particulate oxamide containing mineral, iron sulfate, and phosphoric acid produced by the inclined Erich mixer. It was revealed that it exerts an effective fertilizer effect.

(Example 7) Comparison of granulation time 20 parts by weight of oxamide powder was put into a mixing pan container of a tilt type Erich mixer (Intensive mixer R02 type, manufactured by Nippon Erich Co., Ltd.), and then the modified PVA10 prepared in Example 1 was added. % Liquid was added and mixed for 1 minute at a peripheral speed of the rotor of 6 m / s (900 rpm). Next, 3.20 parts by weight of water is added, and dispersion / granulation is performed at a peripheral speed of the rotor of 19 m / s (3000 rpm) for 5 minutes, 10 minutes or 15 minutes, and a peripheral speed of the rotor is 6 m / s (900 rpm). And treated for 30 seconds, and then discharged. The discharged granules were dried in a dryer at 105 ° C. for 4 hours, and the particle size distribution was measured.
Table 5 shows the measurement results of the particle size distributions (the weight on the 1 mm sieve and on the 1 mm, 2 mm, and 4 mm sieves was divided by the total weight and expressed as a percentage).

  As shown in Table 5, when the granulation time after the addition of the modified PVA and water is 5 minutes and 10 minutes, the amount of granular oxamide of 2 mm to 4 mm is small, whereas when the granulation time is 15 minutes, 50% or more of granular oxamide of 2 mm to 4 mm was obtained.

DESCRIPTION OF SYMBOLS 1 High speed stirring mixer 2 Mixing pan 3 Mixing tool 4 Scraper

Claims (8)

The mixture containing 0.5 parts by weight or more of polyvinyl alcohol or modified polyvinyl alcohol with respect to 100 parts by weight of the oxamide powder was placed in an inclined mixing pan container, and after the addition of polyvinyl alcohol or modified polyvinyl alcohol and water, the rotor was A method for producing granular oxamide, comprising : granulating at a peripheral speed of 15 to 35 m / s with high-speed stirring for 15 to 45 minutes, followed by drying.   A mixing pan that rotates, a mixing tool that is arranged at a position eccentric from the center position of the mixing pan, that rotates independently of the mixing pan, and a scraper that is fixed and arranged inside the mixing pan. The production method according to claim 1, wherein high-speed stirring granulation is performed using a high-speed stirring mixer. The mixture containing 0.5 parts by weight or more of polyvinyl alcohol or modified polyvinyl alcohol with respect to 100 parts by weight of the oxamide powder was placed in an inclined mixing pan container, and after the addition of polyvinyl alcohol or modified polyvinyl alcohol and water, the rotor was In a method for producing granular oxamide, which includes agitation at a peripheral speed of 10 to 40 m / s, high-speed stirring and granulation for 13 to 60 minutes, and drying , the granular oxamide before sieving has a particle size of 2 to 4 mm. The above production method, comprising at least 50% of particulate oxamide. A mixing pan that rotates, a mixing tool that is arranged at a position eccentric from the center position of the mixing pan, that rotates independently of the mixing pan, and a scraper that is fixed and arranged inside the mixing pan. The production method according to claim 3, wherein the high-speed stirring granulation is performed using a high-speed stirring mixer. The method according to claim 3 or 4 , wherein the high-speed stirring granulation is performed for 15 to 45 minutes at a peripheral speed of the rotor of 15 to 35 m / s. The production method according to any one of claims 1 to 4 , wherein the high-speed stirring granulation is performed at a peripheral speed of the rotor of 15 to 35 m / s for 20 to 45 minutes. After feeding the fertilizer raw material containing oxamide into the apparatus, the peripheral speed of the rotor is set to 1 to 10 m / s, and the raw materials are mixed and homogenized, and then the polyvinyl alcohol or modified polyvinyl alcohol liquid and the added water are added. The production method according to any one of claims 1 to 4 , wherein the high-speed stirring granulation is performed at a peripheral speed of 15 to 35 m / s for 15 to 45 minutes. After feeding the fertilizer raw material containing oxamide into the apparatus, the peripheral speed of the rotor is set to 1 to 10 m / s, and the raw materials are mixed and homogenized, and then the polyvinyl alcohol or modified polyvinyl alcohol liquid and the added water are added. The method according to any one of claims 1 to 4 , wherein the high-speed stirring granulation is performed at a peripheral speed of 15 to 35 m / s for 20 to 45 minutes.

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