JPH0316984A - Granular coated fertilizer - Google Patents

Abstract

PURPOSE:To obtain the title slow-acting fertilizer with uniform granular size by coating a granular fertilizer with an organic solvent solution of a synthetic resin followed by extracting only the organic solvent. CONSTITUTION:The objective fertilizer can be obtained by coating a granular fertilizer with a synthetic resin film described below. Said synthetic resin film can be made as follows: the granular fertilizer is coated with an organic solvent solution of a synthetic resin, and in this state, only the organic solvent is extracted with a relevant solution from the coating material. The coating rate of said film is pref. 0.1-50wt.% based on the granular fertilizer. As said synthetic resin, any resin can be used provided that it is an organic linear polymer solid at normal temperature. Said relevant solution is e.g. water or a specific organic solution. A combination of this solution and the organic solvent in which said synthetic resin has been dissolved can be selected as the case may be.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a granular coated fertilizer that can gradually release fertilizer content after fertilization.

[Prior Art] Chemical fertilizers are fast-acting, but because they are essentially water-soluble, losses due to runoff, denitrification, etc. are large, and it is difficult to maintain their fertilizer effects over a long period of time. On the other hand, when applying a large amount of chemical fertilizer at once, there is a risk of solubility problems in agricultural crops. For this reason, various slow-release fertilizers have been proposed in which fertilizers such as chemical fertilizers are formed into granules and coated with a resin film. These proposed methods can be roughly divided into:
It comes down to the following three.

The first method is to dissolve the synthetic resin in an organic solvent, immerse the granular fertilizer in this organic solvent solution, and dry it to form a synthetic resin film around the periphery of the granular fertilizer.

The second method is to melt a resin with a relatively low melting point, mix this melt with granular fertilizer, and form a resin film around the outer periphery of the granular fertilizer.

A third method is to use an aqueous emulsion of a resin and coat the granular fertilizer with this aqueous emulsion.

[Problem that the invention seeks to solve]

However, each of the above three types of methods has the following drawbacks. In other words, in the first method, most of the synthetic resin film formed is non-porous, and therefore, when this is applied, the fertilizer content is not released for a long period of time and the synthetic resin film deteriorates. It has the disadvantage that it is released all at once in stages, making it impossible to obtain a slow-release granular coated fertilizer. Furthermore, in the second method, since the fertilizer is mixed with a melted resin having a low melting point, the fertilizers coated with the melted resin tend to adhere to each other and become large particles. Therefore, there is a problem in that it is difficult to obtain a granular coated fertilizer with uniform grains. In the third method, since the chemical fertilizer is water-soluble, it is almost difficult to form a citrus oil film on the outer periphery of the water-soluble granular chemical fertilizer with a water-based emulsion at a predetermined coverage rate. Therefore, although it is possible on a laboratory scale, it has not yet been put to practical use.

The present invention was made in view of the above circumstances, and its purpose is to provide a granular coated fertilizer that has slow release properties and has uniform grains.

[Means for Solving the Problems] In order to achieve the purpose of item 2, the granular coated fertilizer of Part 19j is a granular coated fertilizer in which the granular fertilizer is coated with a resin film, and The resin film is formed by applying an organic solvent solution of a synthetic resin to granular fertilizer, and then extracting only the organic solvent from the applied body with a solution that can extract only the organic solvent. Take power.

[Effect]

In other words, this invention is a solution in which a solution of synthetic resin in an organic solvent is applied to granular fertilizer, and in that state, the organic solvent is extracted, and only the organic solvent is extracted from the applied body. Since a resin film is formed around the outer periphery of the granular fertilizer by extraction, traces of organic solvent extraction are distributed over the raw resin film as fine pores. In the past, when fertilizer was applied, a constant amount of fertilizer components were constantly released from the micropores, resulting in slow-release properties (gradual release of fertilizer ingredients). . As a result, it becomes possible to realize an ideal fertilization mode.

The granular coated fertilizer of the present invention comprises a synthetic resin for forming a film, a S-containing melt for melting and suspending the synthetic resin, a solution capable of extracting only the organic solvent from the applied body, and a film. Obtained using target granular fertilizer.

As the synthetic resin, any organic linear polymer that is solid at room temperature can be used.

For example, epoxy resin, polyurethane, polyethylene, polypropylene, polycarbonate. Diaryl phthalate resin, melagone resin, polyester, polystyrene acrylic resin. Polyacetal. Examples include polyvinyl acetate, phenolboria chloride, polycellulose acetate, and polyvinyl chloride, which may be used alone or in combination.

Examples of the organic solvent for dissolving the synthetic resin include toluene, hensen, xylene, hebutane octane, ethylcyclohexane, trichloroethylene. Examples include te[-lachlorethylene methylchloroform, carbon tetrachloride, ethane tetrachloride, and tetrahydride 1-7 furan. These organic solvents may be used alone or in combination.

In addition, the organic solvent solution of the synthetic resin can be applied to granular fertilizer and the organic solvent can be extracted in that state using only an organic solvent that does not dissolve the synthetic resin but also dissolves it. An extractable solution is used. for example,
Can be filled with water or certain organic solvents. The combination of rice water or a specific organic solvent and an organic solvent capable of dissolving the synthetic citrus resin can be appropriately selected from conventionally known combinations.

In addition, the granular fertilizer to be covered with the above-mentioned resin film is
It is not particularly limited. This applies not only to chemical fertilizers but also to natural fertilizers if they are granulated. In this case, the average particle size of the granular fertilizer is not particularly limited, but it is preferably set within a particle size range of about 2 to 50 mm in order to avoid large particles.

Although the concentration of the organic solvent solution of the synthetic resin is not particularly limited, it is preferably set to 5 to 30% by weight (hereinafter abbreviated as "%") from the viewpoint of coating work. Also,
In order to improve the affinity of the obtained granular coated fertilizer with water, it is also possible to add various additives such as surfactants to the above-mentioned composite resin film. Furthermore, in order to prevent the granular coated fertilizer from floating on the water surface or from becoming large particles, it is also possible to appropriately add an amorphous filler such as talc or calcium carbonate to the organic solvent solution of the synthetic resin.

The granular coated fertilizer of the present invention can be produced using the above-mentioned raw materials, for example, in the following manner. That is, select any synthetic resin from the synthetic resins exemplified above,
This is dissolved in the above organic solvent to prepare an organic solvent solution of the combined resin. Next, a solution of the synthetic resin in an organic solvent is applied (coated) to the granular fertilizer. This coating is performed in the following manner. That is, (1) Dipping the granular fertilizer into the organic solvent solution of the synthetic resin mentioned above, or (2) Putting the granular fertilizer in a rotary pot and then scattering the organic solvent solution of the synthetic resin into the pot without rotating the rotary pot. This can be carried out repeatedly, or by (2) pouring an organic solvent solution of synthetic resin into a hot air fluidized tank and introducing granular fertilizer into it. The synthetic resin is not dissolved before the organic solvent volatilizes, and the fs. In water or an ia solvent from which only the solvent can be selectively extracted,
The above-mentioned coated granular fertilizer is immersed, etc. As a result, only the organic solvent contained in the coating layer is extracted, and a resin film is formed on the outer peripheral surface of the granular fertilizer. In this case, it is preferable to set the coverage rate of the synthetic resin film on the granular fertilizer to be in the range of 0.1 to 50%, preferably 0.1 to 10%. Here, the coating coverage (%) is defined as follows.

By setting the coverage within the above range, a synthetic resin film can be formed on the outer periphery of the granular fertilizer in a suitable state. That is, if the coverage is less than the above range, the effect of forming a synthetic resin film in this invention will be extremely small, and if it exceeds the above range, the slow-release properties will be lacking, and the non-porous resin film will not be effective. This is because there is a tendency for the same result to be obtained when the outer periphery of granular fertilizer is shaped.

When forming a synthetic resin film on the outer peripheral surface of granular fertilizer in this way, the granular fertilizer coated with an organic solvent solution of synthetic resin is immersed in a solution that can extract only the organic solvent. Since only the organic solvent is extracted from the coated body and formed into a film, the formation of the synthetic resin film is much faster than with conventional hot air drying methods. In addition, it is also possible to control the elution rate of fertilizer substances from granular fertilizer by adjusting the coating resin, organic solvent, and coverage rate used.
This makes it possible to stably supply the fertilizer components necessary for the growth of crops over a long period of time.

[Effects of the Invention] As described above, the granular coated fertilizer of the present invention can be obtained by applying an organic solvent solution of a synthetic resin to the granular fertilizer, and then immersing it in a solution from which only the organic solvent can be extracted. The synthetic resin film is formed by extracting only the organic solvent from the above-mentioned coated body, and since it is covered with this form film, the synthetic resin film has traces of extraction of the organic solvent as fine pores all over the surface. It is in a distributed state. Therefore, fertilizer components are gradually released to the outside through the micropores, making it possible to achieve stable fertilization over a long period of time.

In addition, by selecting the type of synthetic resin and the type of organic solvent, and further adjusting the coverage rate of the resin film, it is possible to control the elution rate of fertilizer components, thereby improving the effectiveness of agricultural products. It becomes possible to adjust the elution rate of fertilizer to the optimum rate.

Next, examples will be described.

[Example 1] 20 parts by weight of cellulose acetate (hereinafter abbreviated as "parts"). 80 parts of acetone was mixed and the mixed solution was placed in a stainless steel container l as shown in FIG. Then, a stainless steel silk basket 4 containing 300 g of urea granular fertilizer 3 having an average particle size of 3 mm was dipped into the mixed solution 2 in the container 1 and immediately pulled out. Then, as shown in Fig. 2, they were placed in a stainless steel mesh basket 3 and immersed in running water 5 to 10 for 3 minutes, then pulled out, and then granular fertilizer was spread on the hearts 1 to 1 (not shown) and It was dried with hot air at °C for 10 minutes. As a result, a granular coated fertilizer with a coverage rate of 2% was obtained. Fertilizer dissolution rate (hereinafter abbreviated as "dissolution rate") when this fertilizer is immersed in water at a temperature of 30°C for 24 hours.
was 6.5% by weight.

The thus obtained granular coated fertilizer has, as shown in the schematic diagram of FIG. 3, fine pores 7 formed from acetone extraction traces distributed over the synthetic resin film 6.

(Example 2) 10 parts of polyimide and N-methyl-2-pyrrolidone (NMP) were added as an organic solvent solution to less than 1 stainless steel container.
A mixture of 90 parts? 8 liquids were used. Except for this, a granular coated fertilizer was obtained in the same manner as in Example 1. The coverage rate of the obtained fertilizer was 5.5% and the elution rate was 0.3%.

[Example 3] A solution of 730 parts of polystyrene and 70 parts of toluene was used as the organic solvent solution of the synthetic resin, and methanol was used instead of water as the organic solvent extraction solution. A granular coated fertilizer was obtained in the same manner as in Example 1 except for the above. The coverage rate of the obtained fertilizer was 12% and the elution rate was 2.2%.

[Example 4] As an organic solvent solution of the synthetic resin, a mixed solution of 25 parts of styrene chloride (SBS) and 75 parts of 1.luene was used. In addition, as a solution for extracting the container,
Methanol was used instead of water. Other than that, Example 1
Granular coated fertilizer was obtained in the same manner as above. The coverage rate of the obtained fertilizer was 7% and the elution rate was 6.5%.

[Example 5] As an organic solvent solution of a synthetic resin, a mixed solution M of 27 parts of n-polybutyl methacrylate and 65 parts of ethyl acetate was used. Except for this, a granular coated fertilizer was obtained by C straining in the same manner as in Example 1. The coverage rate of the obtained fertilizer was 12% and the elution rate was 25%.
Met.

[Example 6] A mixed solution of 15 parts of ethylene-hinyl acetate 11 12 acid copolymer and 85 parts of toluene was used as the aqueous solvent solution of the polymerization resin. Furthermore, methanol was used instead of water as the organic solvent extraction solution. A granular coated fertilizer was obtained in the same manner as in Example 1 except for the above. The obtained fertilizer has a coverage rate of 6.3%
The elution rate was 43%.

The elution rate curve when the granular coated fertilizer obtained in Example 1 above was immersed in water at 3oC was compared to cellulose acetate 20
Fig. 4 shows a comparison with that of a granular coated fertilizer in which a non-porous film was formed using a porous solution containing 80 parts and 80 parts of acetone. Curve A is that of the granular coated fertilizer of Example 1, and curve B is that of the comparative example. As is clear from the comparison between curves A and B, it can be seen that the granular coated fertilizer of the example sufficiently maintains slow-release properties.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams for manufacturing a granular coated fertilizer according to an embodiment of the present invention, Figure 3 is an enlarged plan view of the granular coated fertilizer obtained thereby, and Figure 4 is a dissolution rate IHI diagram. be. 2... Mixed solution 3... Granular fertilizer 6... Synthetic resin film 7... Fine pores

Claims (2)

[Claims] (1) A granular coated fertilizer in which a granular fertilizer is coated with a synthetic resin film, wherein the synthetic resin film applies an organic solvent solution of the synthetic resin to the granular fertilizer and extracts only the organic solvent in that state. A granular coated fertilizer characterized in that it is formed by extracting only the organic solvent from the above-mentioned applied body using a liquid solution. (2) Coverage ratio of synthetic resin film to granular fertilizer is 0.1
The granular coated fertilizer according to claim (1), wherein the granular coated fertilizer is set to 50%.