JPH09227258A - Production of molded fertilizer and molded fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing s molded fertilizer which further improves the slow release property of the slow-release fertilizer, and further, improving the underwater shape-retaining property at the time of irrigation, etc., by treating a urea-acetaldehyde condensed fertilizer by a specific method. SOLUTION: Water is compounded at 3 to 10wt.% with the urea-acetaldehyde condensed powder and granular materials and the compd. is press molded by a molding machine of 0.5 to 10tons/cm<2> . The moldings are then subjected to a rapid heat treatment at 50 to 150 deg.C. As a result, the molded fertilizer which does not collapse in the water of 80 deg.C and 24 hours is obtd. The urea- acetaldehyde condensed powder and granular materials are directly synthesized from urea-acetaldehyde and contains a cyclic compd. of a 2 oxo-4 methyl-6 ureide hexahydropyrimidine structure and others, such as unproduct urea, aldehyde, dimer, etc., and are satisfactory if an N warranty value is satisfied at pH >=4.5.

Description

Detailed Description of the Invention

[0010]

TECHNICAL FIELD The present invention relates to a method for producing molded fertilizer and a molded fertilizer. More specifically, the present invention relates to a method for producing a molded fertilizer and a molded fertilizer having further improved slow-acting properties of a slow-acting fertilizer and improved shape retention in water during irrigation.

[0011]

[Prior art] Labor-saving has increased due to the aging of the agricultural population and the shortage of successors, and slow-release fertilizers have been developed. A slow-release fertilizer has been developed as an effective use method for preventing the above-mentioned problems. Generally, the methods for slowing down fertilizer can be roughly classified into the following two methods. Coated fertilizer: A method of physically controlling the elution of fertilizer components by granulating the fertilizer and coating the whole with a sparingly water-soluble or water-repellent substance. Slow-release nitrogen fertilizer: a method of chemically treating water-soluble nitrogen, water-soluble phosphoric acid, water-soluble potassium, etc. to make it slow-release, and the one that has been put to practical use is urea-formaldehyde condensate (ureaform), Urea-isobutyraldehyde condensate (IB / IBDU),
There are five types: urea-acetaldehyde condensate (CDU), dicyandiamide-phosphoric acid condensate (guanylurea), and ammonia-hydrocyanic acid condensate (oxamide). Further slow-acting nitrogen fertilizer IBDU
As a combination of the above and fertilizer, there are known Japanese Patent Publication No. 54-24942 which is mixed with a mineral heavy oil and Japanese Patent Publication No. 59-24117 which is incorporated with a low olefin polymer. Urea-acetaldehyde condensate (CDU)
Is often used as a good slow-release nitrogen fertilizer. Furthermore, as a fertilizer coated with urea-acetaldehyde condensate (CDU), JP-A-63-17285 and JP-A-63-2.
The 5288 publication is known. There is no known urea-acetaldehyde condensed fertilizer that does not disintegrate in water without coating.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a molded fertilizer in which the slow-release property of a slow-release fertilizer is further improved and the shape retention in water during irrigation is improved, and the molded fertilizer thereof. is there.

[0013]

Means for Solving the Problems Hereinafter, the present invention will be described more specifically. 1. Add water to urea-acetaldehyde condensation powder 3-10
% By weight, and this mixture was pressure-molded with a molding machine of 0.5 to 10 ton / cm ² , and the pressure-molded product was heated to 50 to 150 °
A method for producing a molded fertilizer, which comprises performing rapid heating treatment with. 2. A molded fertilizer which is obtained by rapidly heating a pressure-molded product of a water-containing-urea-acetaldehyde condensation powder and does not disintegrate in water at 80 ° C. for 24 hours.

The urea-acetaldehyde condensate powder used in the present invention is directly synthesized from urea-acetaldehyde. It contains the products urea, aldehyde, dimer and the like. This urea-acetaldehyde condensate powder is commercially available and is customarily called CDU.
Further, it does not specify the purity but may satisfy the N guarantee value at PH 4.5 or more. It is preferable that PH is 4.5 or more because it is not hydrolyzed. When pH adjustment is required, a pH adjusting agent such as weakly alkaline CaCO3 or NaHCO3 may be added.
The size of the powder and granules is preferably a size that can pass through a 3 mm opening sieve, and may be mixed with agglomerates with a low hardness and a large crushability. In the case of obtaining doublet size, a powdery or granular material size that can pass through a 1 mm sieve is preferable from the viewpoint of filling property and impregnation property with water, and in order to obtain briquette size, a particle size that can pass through a 2-3 mm sieve is more preferable.

The water used in the present invention may be general water, or may be a commercially available industrial water level. The amount of water blended is 3-10% by weight, preferably 5-8% by weight in the formulation.
When the compounding amount is within this range, there is no adhesion or blocking such as blocking in the manufacturing process, and the shape retention property of the molding fertilizer in water is good. In the pressure molding of the present invention, the water-containing composition is 0.5 to 10 ton / cm.
Mold with ² molding machine. As the pressure molding machine, a granulation machine, a tablet machine (tablet machine), a roll press (briquette machine), or other suitable molding machine may be selected. The molding conditions are 0.5-10 ton / cm ² ,
Preferably 4-8 tons tablet size of the cross-sectional area 1-2.3cm ² / cm ^2, blanking sectional area 3-27Cm ² Rikettosaisu゛De 1-3 ton / cm ²
Pressurize. Within this range, an excellent underwater shape retention property can be obtained, which is preferable in terms of equipment cost and power cost.

The rapid heating treatment of the pressure-molded product in the present invention is to heat the water-containing compound at 50 to 150 ° C. for a short time, and to heat at 0.5 to 5 hours at 50 to 150 ° C. The heating is preferably performed for 1 to 3 hours. Within this range, it is possible to obtain a molded fertilizer having excellent shape retention in water, no problem in heat resistance of impurities, and economical efficiency.
In the molded fertilizer of the present invention, in addition to the urea-acetaldehyde condensation powder, fertilizer elements necessary for plant growth, natural and synthetic adhesives / binders, oils, pigments, dyes, fragrances, antibacterial agents, antifungal agents. Among the agents, insecticides, plant growth regulators, plant hormones, water retention agents, etc., those having a small solubility in water and those having heat resistance for a short time can be appropriately added. Further, the shaped fertilizer of the present invention does not disintegrate in 1 liter of standing water in 1 liter of fertilizer at 80 ° C. for 24 hours. Preferably the amount dissolved, the amount dissolved per day is 0.
1 (g / fertilizer 1g / 80 ° C water 100cc) or less,
Furthermore, it is 0.01 or less and 0.001 or more. Further, the size of the shaped fertilizer of the present invention is preferably 0.1 to 100 cm ³ , and can be selected from tablets, rods, granules, etc. according to the application.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various investigations, the inventors of the present invention rapidly heat-treat a pressure-molded product of urea-acetaldehyde condensed powder and water to obtain a molding fertilizer having a shape-retaining property in water. I found that I can get. It is believed that the reason for its excellent shape retention in water is as follows. The solubility of urea-acetaldehyde condensate powder is 0.08g / 100g water at 20 ° C and 1.6 at 90 ° C.
It is 5g / 100g water and there is a 20 times difference. The rapid heating treatment dissolves the surface of the urea-acetaldehyde condensate powder with water, and the evaporation of the water causes the urea-acetaldehyde condensate in the aqueous solution to crystallize, bridging the surface of the granule. It seems that the secondary agglomerates are solidified, but this has not been fully clarified.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 Urea-acetaldehyde condensate powder of CDU (trade name) manufactured by Chisso Corporation was passed through a 1 mm sieve, and 1 g of this passing product was treated with tap water.
053 g was added and mixed, charged into a Teflon-coated cylinder with a cross-sectional area of 1 cm ² , deaerated with slidable histones, and compression-molded with a hydraulic pressure of 5 ton / cm ² so as to achieve the closest packing. Immediately after compression molding, the mixture was put into a hot air drying furnace controlled at 120 ° C, dried for 2 hours, taken out, and allowed to cool to obtain a molded fertilizer. Example 2 Urea-acetaldehyde condensed powder of CDU (trade name) manufactured by Chisso Corp. was passed through a 3 mm sieve, and 2.3 g of industrial water was added and mixed with 21 g of this passing product, and the mixture was inserted into a slidable cylinder. It was put between the inner Teflon-coated halved coal corps dies with a cross-sectional area of 10.7 cm ² , degassed with a piston connected to the halved dies, and with a hydraulic pressure of 1.5 ton / cm ² to achieve the closest packing. Immediately after compression and demolding, the product was put into a hot air drying furnace whose temperature was controlled to 100 ° C., dried for 5 hours, taken out, and allowed to cool.

Comparative Example 1 The same operation as in Example 1 was carried out except that water was not added to 1 g of a 1 mm sieve pass product. Comparative Example 2 Same as Example 1 except that the molding pressure was 10 ton / cm ² and the drying conditions were 40 ° C. and 8 hours. Comparative Example 3 21 g of 2 mm sieve-passed product for briquette with 3.7 g of tap water
Was added and mixed, and thereafter, the molding pressure was set to 0.1 ton / cm ² , and the drying condition was set to 120 ° C. for 3 hours.

Evaluation of the above-mentioned molded fertilizer was carried out by 80 ° C. accelerated shape retention in water. The basic factor of the fertilization rate is the degree of solubility in water, and the solubility mainly depends on the temperature. Therefore, considering the heat resistance, the measurement time was shortened to 80. The evaluation depended on the appearance change and the dissolution amount. The appearance change was evaluated by observing changes in the surface condition of the molded body such as cracking and collapse as changes with time. Cracks are often caused by molding stages such as capping, laminating, binding, clamshell, etc., but the surface area increase rate by these is not large. The amount of dissolution was measured by the following method. Inject 1 liter of pure water at 80 ° C into the beaker, then add 1 each of fertilizer and cover the top opening of the beaker with a polyolefin film to prevent water evaporation. The beaker was placed in a thermostat set at 80 ° C., the molding fertilizer was dissolved, and the amount of dissolution was obtained every 24 hours by directly measuring the amount of dissolution. Pure water is 24 hours
I replaced it every time. Those having water-insoluble content were determined by the dissolution rate ratio. The fertilizer disintegration period was measured, and the fertilizer input amount was divided by the number of period days to obtain the dissolved amount per day, which was defined as 1 g of the fertilizer.

Results of evaluation of shape retention in water during accelerated irrigation at 80 ° C.

[Table 1]

[0022]

EFFECTS OF THE INVENTION The molded fertilizer of the present invention has improved slow-release properties, shape retention in water during irrigation, etc., and can be expected to further save labor and effectively use the fertilizer. In addition to mitigation, it can be widely used as a good slow-release nitrogen fertilizer with physiologically active effects on plants and microorganisms, improvement of physical properties of soil by continuous use, and reduction of continuous crop damage.

Claims (2)

[Claims] 1. A urea-acetaldehyde condensation powder and granules are mixed with water in an amount of 3 to 10% by weight, and the mixture is pressure-molded by a molding machine of 0.5 to 10 ton / cm ² to obtain a pressure-molded product. 50
A method for producing a molded fertilizer, which comprises performing rapid heating treatment at 150 ° C. 2. A pressure-molded product obtained by mixing urea-acetaldehyde condensed powder and water with water is subjected to a rapid heating treatment and at 80 ° C.
Molded fertilizer that does not disintegrate in standing water for 24 hours.