JPH0733577A - Coated granular fertilizer composed of poly-l-lactic acid film - Google Patents

Abstract

PURPOSE:To control the elution of a fertilizer component without any remaining film shell under hardly any load on the natural environment by coating the granular fertilizer component with a biodegradable poly-L-lactic acid. CONSTITUTION:The poly-L-lactic acid used in this method is expressed by formula (1) [(n) is 1000-15000]. This coated granular fertilizer is obtained by dissolving or dispersing poly-L-lactic acid in a solvent such as a chlorinated hydrocarbon-based or a ketonic solvent or a dispersing agent, spraying the resultant solution or dispersion to a granular fertilizer, simultaneously blowing a high-speed hot-air stream at the sprayed position and instantaneously drying the solvent or the dispersing agent. The formed film is capable of regulating the elution of the fertilizer and undergoing the degradation with a microorganism without remaining in soil. The coating ratio of the coating material is preferably 5-25wt.%. The lower figure indicates one example of an apparatus for producing this fertilizer. Air for blowing is fed from a blower 10 and passed through an orifice flowmeter 9 and a heat exchanger 8 and reaches a jet column 1. The granular fertilizer to be subjected to the coating treatment is charged from a charging inlet 2 while passing hot air therethrough. Thereby, a jet stream is formed. A coating solution is passed from a tank 11 to a nozzle 4 and sprayed on the granular fertilizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated granular fertilizer which controls the elution of fertilizer components and is rapidly decomposed by microorganisms after the elution is completed so that the film shell does not remain in the soil.

[0002]

2. Description of the Related Art It has been studied to coat fertilizer with various polymers and coating materials. For example, Japanese Examined Japanese Patent Sho 40
Various materials have been proposed in Japanese Patent No. 28927, Japanese Patent Publication No. 42-13681, etc., but it was difficult to control the elution rate of fertilizer components. In addition, attempts have been made to disperse inorganic powder such as sulfur and talc in a low molecular weight olefin polymer to accelerate the disintegration of the coating material while maintaining the elution control function (for example, Japanese Patent Publication No. 60-3040). No., JP-A-55-1672
Etc.). However, the film shell does not completely decompose and the coating material remains in the soil. Alternatively, there is a case where the fertilizer grain shape is broken during transportation or loading work because the strength of the coating material is not sufficient.

[0003]

The object of the present invention is to control the elution of fertilizer components from the granular fertilizer, and after the elution is completed, the coating material is decomposed by microorganisms and does not remain in the soil. Is to provide.

[0004]

As a result of intensive studies, the present inventor has found that the above-mentioned problems can be achieved by using a poly-L-lactic acid film as a coating material. That is, the present invention is a coated granular fertilizer characterized by being coated with a biodegradable poly-L-lactic acid film represented by the following formula (1).

[0005]

[Chemical 2]

The raw material of poly-L-lactic acid used in the present invention is lactic acid produced by microorganisms, and oligolactic acid, which is an intermediate decomposition product of poly-L-lactic acid, is known to promote plant growth. There is. As described above, the poly-L-lactic acid used in the present invention as a coating material is also excellent in environmental protection. The coated granular fertilizer of the present invention sprays a liquid obtained by dissolving or dispersing the coating material (poly-L-lactic acid) in a solvent such as a chlorinated hydrocarbon type or a ketone type onto the granular fertilizer, and at the same time, high-speed hot air flow It is obtained by instantly drying the solvent or dispersant by spraying. This coating is
It regulates the elution of fertilizer and is not retained in the soil due to microbial degradation.

The coating rate of the coating material of the present invention is preferably in the range of 5 to 25% (by weight) from the viewpoint of adjusting the elution rate.
Of course, other coating materials, surfactants, talc, pesticides, calcium carbonate, etc. that can be mixed can be mixed and used as needed. It is necessary to disperse these uniformly, and if they are not uniform, the dissolution rate of the fertilizer component will be disturbed.

[0008]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

[0009]

Example 1 Apparatus and Manufacturing Method FIG. 1 is an example of a suitable apparatus for manufacturing the coated granular fertilizer of the present invention. In FIG. 1, 1 is a jet tower, for example, the size is a tower diameter of 200 mm, a height of 1800 mm, and an air jet diameter of 42 m.
m, 2 is a fertilizer injection port, and 3 is an exhaust gas ejection port.

The jet air is sent from the blower-10,
Although it reaches the jet tower through the orifice flow meter 9 and the heat exchanger 8, the flow rate is controlled by the flow meter and the temperature is controlled by the heat exchanger, and the exhaust gas is guided from the exhaust gas jet port 3 to the outside of the tower. The granular fertilizer to be used for the coating treatment is introduced from the fertilizer introduction port 2 while passing a predetermined hot air to form a jet flow. In the coating process, after the temperature of the coated particles reaches a predetermined temperature, the poly-L-lactic acid-containing coating liquid is sprayed through the liquid nozzle 4 toward the jet stream in a spray state. The coating liquid is prepared by putting a predetermined amount of the coating material and the solvent in the liquid tank 11 and stirring the mixture near the boiling point of the solvent. The supply of the coating liquid is sent to the nozzle 4 by the pump 5, but this system is kept warm enough to maintain the temperature. When the predetermined coating liquid is supplied, stop the pump and stop the blower. The coated fertilizer is taken out from the outlet 7. 6 is a valve. In FIG. 1, T ₁ , T ₂ ,
T ₃ is a thermometer and SL is a steam. In this example, the granular fertilizer was coated under the following basic conditions.

Liquid nozzle: Opening, 0.8 mm, full-con type hot air flow rate: 4 m ³ / min Hot air temperature: 30 ° C. Fertilizer type: 5-9 mesh Phosphorus nitrate Akari Fertilizer input amount: 5 Kg Coating liquid concentration: Solid content 3 Weight% Coating liquid supply rate: 0.5 Kg / min Coating time: 35 minutes Coverage rate (against fertilizer): 5.5% by weight Solvent: Trichlorethylene With this device, the granular surface was finely coated with poly-L-lactic acid film. The coated granular fertilizer could be obtained.

[0012]

Example 2 Measurement of Nitrogen Elution Amount With the above-described manufacturing method, coated phosphorous nitrate Akari with various coating ratios (adjusted by changing the amount of fertilizer input and the amount of coating liquid supplied) was produced, and Nitrogen elution amount (25 ℃)
Was measured and the results are shown in Table 1.

As a comparative example, a non-microbial degradable membrane: polyethylene 20 parts, ethylene / vinyl acetate copolymer-30
Part, talc 50 parts, coverage 7%.

[0014]

[Example 3] Degradability test of coating in soil No. 1 to 4 coated phosphorous nitrate Akari 30
Each grain was cut on two sides and allowed to stand in water to sufficiently remove fertilizer components inside to form a ring-shaped film.

The soil is 2m of fertile diluvial soil (Fuji City).
The soil that passed through the m sieve was used as the test soil. Put the test soil in a horticultural planter as a bed, and embed the ring horizontally in the bed at a depth of about 1 to 3 cm,
It was installed in a glass greenhouse. Sprinkle water occasionally to prevent the bed from drying out. We dig this out 1, 3, 6, 9 months later,
The state of the ring was visually observed and the strength was measured. The observation conditions are shown in Table 2, the change over time in strength is shown in FIG. 2, and the change in strength retention rate is shown in FIG.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

INDUSTRIAL APPLICABILITY The coated granular fertilizer of the present invention is coated with a biodegradable poly-L-lactic acid film, the elution of fertilizer components is controlled, and no film shell remains after the elution is completed. It has features. Therefore, it is an excellent agricultural material with less impact on the natural environment.

[Brief description of drawings]

FIG. 1 is an apparatus diagram for producing coated granular fertilizer according to the present invention.

FIG. 2 is the time course of the strength of the coated membrane ring according to the present invention in soil.

FIG. 3 is a time-dependent change in the film strength retention rate of the coated film ring according to the present invention in soil.

Claims (1)

[Claims] 1. A coated granular fertilizer which is coated with a biodegradable poly-L-lactic acid film represented by the following formula (1). [Chemical 1]